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Psyche 9:207-212, 1900.

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PSYCHE.
STUDIES FOR STUDENTS,
I.
THE ANATOMY OF THE LARVA 01'' THE GIANT CRASE PLY (monisia rtthjgim~a). BY VEl<KON L. KET.LOGG, STANFORD UNIVERSITY, CALIF. PREFATORY NOTE. It has long seemed to the writer that It is the writer's intention to present
under the title "Studies for Students"
a series of short papers which shall offer to students an introduction to woik in
certain of those phases of insect study
which are likely to be negleclcd by
amateur entomologists, especially those
who have not been members of collegi-
ate classes in zoology or entomology.
There will be presented in each
paper a small piece of work in the
study of insect structure, development
or physiology, in such a manner as to
serve as a practical exercise or lesson
which can either be directly repeated by the entomological student without other
professional instruction, or can be used as an example and reference for the
performance of similar work with some
other species of insect. In the case of
each of these papers (which will appear
irregularly) the actual facts recorded
will be new, i.e., the result of observations not heretofore recorded. Thus these
papers may have a value to entoinolo-
gists who are not specially interested in a "guide for self-instruction." The
strictly technical directions to students will be enclosed in brackets.
the almost exclusive attention of most
amateur entomologists (and amateurs
constitute the great majority of the
total number of entomologists) to sys-
tematic work, the finding, preserving,
identifying and describing of species,
is a fact to be deplored.
There is so
much that is interesting and profitable
to be studied in the structure, develop- ment and ecology of insects, that it is a pity that the systematic phase of insect study should monopolize such a large
proportion of the work of the whole body OF entomologists.
It is with the thought
that a few examples of the other phases
of entomological work put into a sort of teaching manner may perhaps help some
amateurs to make a beginning in other
lines than the purely systematic one
that these ccStudies for Students" are
written.
ANATOMY OF THE LARVA OF TI^^^^^^^^
RUBIGINOSA,
The larvae of the Giant Crane-fly,*
*The immature stages of Hoh~sisia. ynbig^iwma have not hitherto been relerred to in print. The life-history of this largasi known Dipteron with a descriptioia of theimmature stages will be made the subject of a brief paper in some futwe iaumbcr of PSYCHE.




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208 PSYCHE. [June, ,001
Hdorusia rz;h&r;osa, are found abun-
dantly in a slime composed of decaying
leaves and soil and water on the banks
of Adalanta Creek near this University
(Stanford). The larva is so large, full- grown specimens averaging about 2 to
23 inches in length, and the character
and disposition of its internal organs so readily and certainly made out in dis-
section, that it is chosen as subject for a short study of internal insect anatomy.
As IIolorusia does not occur elsewhere
in the United States than on the Pacific Coast (as far as is known) students in
other regions will have to use the larva of some other Tipulid species. Some
rather large Tipulid is common in almost every locality, and the use of another
species than the one whose structure is
here described will make the work to
some extent comparative in character
and thus be even more instructive and
interesting than if the same subject
could be * used. The account of Halo-
rush will be found to answer as a guide
to the dissection of any other Tipulid
larva.
External Anatomy (Fig. A).
Technical note. Bring a number of the
larvae of some large Tipulid species
(found in vegetable slime, or about grass roots in pastures, etc.) alive into the
laboratory. Note the various motions
and the locomotion of the body. Kill
*I shall be glad to send to any one, two specimens of fZolorusia larvae, properly killed for dissection, if tine postage and actual cost of the wooden mailing' bottles, amounting to about (?) cents, are paid by the applicant. specimens by dropping into boiling water. After the specimen has straightened out
and stiffened, requiring about a minute, (death is almost instantaneous) remove
to 30% alcohol. After two or three
hours remove to 50% alcohol, and after
three hours into 70% alcohol. After
twelve to twenty-four hours remove to
85% alcohol, in which keep the speci-
mens.
[Verify the following statements if
Holorusia .is used ; if another Tipulid
is used compare conditions with those
here dcscribed.] The body is com-
posed of thirteen segments. Retracted
into the first and second segments is the head, with strongly chitinized capsule.
At the anterior endof thc head, usually
projecting slightly, arc the short cylin- drical unsegmented antennae and the
strongly chitinixed biting mouthparts.
(The mouthparts can bc better ex-
amined after the internal anatomy has
been studied and the retracted head
wholly exposed.)
The hindmost body segment bears
terminally on a flat surface two large
dark spiracles (breathing openings) sur- rounded by six backward projecting
flexible lobes. On the ventral surface
of this segment is the anal openihg of
the alimentary canal, on an elevation
bearing four large and two smaller flex- ible processes. The segments of the
hinder half' of the body have each a
median transverse construction ; those
of the anterior half are difficult to dis- tinguish from one another, but it is
assumed that each pair of the lateral




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June, q011 PSYCHE. 209
groups of setae, of which five pairs may rior end four elongated pouches, the be noted, represents a segment. The ab- gastric caeca. In the sheet of adipose sence of all paired appendages back of tissue surrounding the ventriculus sev- the head is to be noted. [Make a draw- eral slender convoluted tubules may ing of the whole body of the
larva from a lateral aspect.]
Internal Anatomy. (Fig. B.)
[å´7khzica note. With fine scis-
sors cut open the body along the
median line of the clorsum, cut-
ting through only the body wall.
Put the specimen in a* dissect-
ing dish, pin out the cut edges
with ribbon pins, and cover
with water.]
Alimenlary canal andaccessorj
parts. The alimentary canal cx-
tends through the middle of the
body cavity, nearly wholly cn-
closed, in a thin perforated shcct
of fat, adipose tissue. The canal
consists, first of a slender lube,
the oesophagus, embraced by the
circ'umoesophogeal nerve corninis-
sures and the bra-& lobes; second,
of an abruptly dilated conical
p o r t i o n , the proventrii-ulus ;
third, of a portion immediately
behind this and not sharply
marked off from it, the elongated
ventriculus, bearing at its ante-
'For a dissecting- dish use a shallow tin dish, about 5 inches long-. 3 inches wide and r inch deep, into which melted pariiffiiie lias been poured to s. depth of 3 inch and allowed to rod On the smooth surface of the paraffine spec~mem may be pinned out wit11 short pins mnd covered wit11 water. Alwap dissect under rater, as the water holdsup the loosened parts. A, larva. B, dissection of larva, showing all organs except the mudes and vcntml nerve c1ni11. h, head: ant., iutmma; i. 6. mr., imaginal bud of respiratory tube ; i. b. wg-., imagiiial bud of wing; i.b. MS. I,, in-iaginal bud of mesoihoracic leg; i. 6. A, imaginal bud of balancer; i.6. mi. I., imaginal bred of rnetathortidc leg (the imaginal buds ol" fore ICES are concealed by head capsule); sal. å£å´I salivary
eland (the other salivary gland is removed); br., brain: om, oesopha- go$; #mv., provc~~triculus: w$, suspensoriurn; E. c., gastric cmcum; vent, ventriculus: ir., trachea; nil /is, adipose tissue; mal. tub., Malpi- ghim tubule; d. v., dorsal vessel; w. PPZ,, wing nmcles of perica~dium; sm. int., small intestine; tes, testis; int. c.,intestinal caecum: v.d., vas deferens; 2. int., large intestine; sp: spiracle: term. pr., terminal processes.




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210 PSYCYLE. [June, iw
be noted; these are the Malp&hian
Utilities, the organs of excretion, four in number. They arise from the alimen-
tary canal just back of the ventriculus
at a part marked by a pale transverse
line. Behind this line is a fourth part
of the alimentary canal, the small intes- tine. It is of smaller caliber than the
ventriculus and opens into the fifth divi- sion of the canal, the large intestine,
near the anterior end of the latter The
large intestine is largest in front and
tapers posteriorly to the very narrow
rectal part. That portion of it in front of the point of entrance of the small intes- tine may be called the iniesfi'~~al caecum. The salivaryglands lie one on each side
of the oesophagus. Kach is a U-shaped
organ with the two arms greatly dilated, and the inner reaching a little farther
forward than the outer. The salivary~
duct arises from the outer lobe ; the two ducts anteriorly unite beneath the oeso- phagus,and the common ductthus formed
opens into the mouth cavity. [Without
removing the alimentary canal make a
drawing of it as seen from one side;
also make a drawing of the salivary
glands and their ducts.]
[Remove a piece of salivary duct to
a drop of water on a glass slide without a cover glass.
Examine with low objec-
tive of compound microscope. Notice
transverse lines. Press on two places
of the duct with dissecting needles and
pull gently apart a very short distance. Examine again under the microscope.
The two parts will probably be con-
nected by a spiral thread; this will be
seen to be what formed the transverse
lines ; it is really a spiral thickening of the walls.]
[Remove a small piece of fat to a
drop of water on a glass slide. Exam-
ine with low power objective. Make a
drawing showing the fcnestrated struc-
ture, the definite outlines, as if the whole were enclosed in a delicate transparent
case, and the small spherical bodies
-the fat cells-within. Put on a
cover glass and examine with the higher
power objective.]
The. mpirdory organs, Lying along
each side of the body is a main longi-
tudinal trachea (air-tube) . Each arises from one of the large posterior spiracles and in each of the third to the ninth
segments forward gives off a large branch to the alimentary canal and a smaller one to the dorsal blood vessel (see below).
[Make a drawing of the tracheal system,
tracing the longitudinal vessels as far
forward as possible.]
[Cut off a piece of one of the lateral
tracheae and remove it to a drop of water on a glass slide under a cover glass.
Examine it with the lower power of the
compound microscope and notice the
tubular appearance and transverse sti-ia- tions as in the salivary duct. The spiral nature of the thickening is not so easily shown as in the other case but it is
characteristic of all insect tracheae.]
The reproductive organs. These con-
sist in the male of two small white oval glands, the testes, lying one on each side of the large intestine imbedded in the
muscles of the tenth segment, and of a




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June, 19011
PSYCHE.
delicate duct, the vas defe'rens, running posteriorly from each to the ventral
wall of the penultimate segment. The
ovaries (of female specimens) are larger and more elongate than the testes and
the oviducts (corresponding to the vasa
deferentia) are more easily seen.
[Make a combined drawing showing
the alimentary canal, salivary glands,
tracheal trunks and reproductive organs
in position in the body].
The ne~uons system .Remove the
alimentary canal culling the oesophagus
across near the front end of the proven- triculus. The brain is composed of two
conspicuous white lobes united poste-
riorly lying above the oesophagus. The
sub-oesopfiageal ganglion lies beneath
and just below the oesophag!~~, and is
connected with the anterior end of the
brain lobes by the circum-oesophageal
commissures. Back of the sub-oeso-
phageal ganglion is a chain of four
closely connected ganglia. The next
ganglion is far removed from the fourth, lying in the sixth segment and is con-
nected with the preceding and following
ganglia by long slender commissures.
Following the fifth ganglion are five
others similar to it, each lying over the center of the sternal part of a segment. Each ganglion gives off four very con-
spicuous nerve tj-nnks; one on each side arising from the middle of the ganglion
going to the muscles of the body wall,
and another arising from the anterior
end of the ganglion going to the viscera- The last ganglion, lying in the antepe-
nultimate segment. in addition to the four lateral trunks gives off from the posteri- or side two large divergent ones caudal
to the two following segments. [Make
a drawing of the nervous system.]
The muscular system.
Along each side
of the dorsal and the ventral median line of the body is a wide band of longitudin- al muscles. The most conspicuous fibers
reach from the exterior to the posterior border of each segment, but the others.
reach from either end to the middle,
while others extend from the middle of
one segment to the middle of the preced- ing or following segment, while still
others are attached to various points of the body wall between the attachments
of the sets already mentioned. Finally
there is an innermost set of lateral trans- verse muscles in the anterior half of
each segment. [Make a drawing show-
ing the musc~~lation of two successive
segments.]
[Remove a bit of muscle to a glass
slide and examine it with the compound
microscope. Note the transverse stria-
tion].
The circulatory system.
[Cut a second
specimen open longitudinally along the
median line of the venter, reserving the first specimen for some later work. Pin
the cut edges out. Note again the gen-
eral disposition of the body organs, so
far examined. Examine again therepro-
ductive organs; the specimen may be of
the other sexfrom that previouslystudicd. .Remove the alimentary canal.] The
dorsalvessel or heart is a slender, deli- cate membranous tube composed of a
- number of parts or chambers lying




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PSYCHE.
along the median line of the back.
[To
see this well cut out the median dorsal
strip of body wall carrying the heart
and transfer it to a glass slide. Cover
with water and examine first under the
simple microscopc and then under the
low objective of the compound micro-
scope.] It will be distinctly seen that
toward the middle of each segment,
from the last to the third inclusive, the tube becomes dilated and in most of
these swellings except the last a pair of internal valves may be seen. From the
anterior of these a straight anteriorly
tapering tube, the aorta, extends for-
ward into the head where it ends in
branches. [Make a drawing of the
heart and aorta.]
Attached to each dilatation of the
heart are two fan-shaped groups, one on
each side, of very delicate muscle
fibers, called zving muscles from their
shape. The convergent outer ends are
attached to the body wall on the line of the median constriction in each seg-
merit. These muscles are easily seen
under the compound microscope.
The imaginal buds of wings and legs.
[ Returning to the first specimen (that
opened along the dorsum) carefully
remove the muscle fibres from the body
wall of the three front (thoracic) seg-
ments of the body, not including the
head. Be careful not to pick away cer-
tain small whitish bud-like bodies lying between the muscles and the body wall.]
In specimens of sufficient age the imw-
in& luds of the wings and legs and of
the external prothoracic respiratory
tubes of the pupa may be seen as small
sac or bud-like bodies lying against and attached to the inner surface of the
body wall of the thoracic segments.
There are two pairs of these imaginal
buds in each thoracic segment corres-
ponding respectively to the prothoracic
legs of the imago and prothoracic re-
spiratory tubes of the pupa, the meso-
thoracic legs and wings of imago, and
the metathoracic legs and halteres of
the imago. The morphology and devel-
opment of these imaginal buds will be
the subject of the next paper in this
series.
The head scle~ites and monthparts.
[After finishing the dissection of the
inlernal organs remove the head entirely from the rest of the specimen and ex-
amine under the simple microscope].
Each of the short antennae arises from
a small lobe on the plate covering
the top of the head. This plate is
long, tapering and decurved bc-
hind. Anteriorly along its sides it is
united with the lateral plates, while the anterior margin is reentrant receiving
the smaller end of the pear shaped
lalimm (upper lip). The distal part of
this sclerite is membranous except for
two lateral chitinizations. Posteriorly
it is fused with the epicranialplate. The lateral plates are each oval, shell-shaped, having their anterior lower angles pro-
duced forward and united with each
other. The single process thus formed
projects forward and curves upward be-
tween the faces of the posterior jaws.
The tips are provided with graduated




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June, 19011 PsYcflE. 213
teeth. In the front of each large lat-
innei side with a large, softer, movable era1 plate is a narrow dorso-ventral lobe. Thc posterior jaw (the maxilla) sclerite carrying the jaws. These are is less chitinous than the other; it is two in number on each side.
The an-
flat and provided at its outer angle with terior one (the mandiI,k) is large, strong, several papilla-like processes.
toothed terminally, and provided on the
GYNANDROMORI'HISM IN A NEW SPECIES OF HILARA.* BY AXEL LEONARD MELANDER, AUSTIN, TEXAS. While collecting insects in Western
Wyoming during September, 1895, Dr.
Wm. M. Wheeler chanced upon a very
remarkable fly. This insect, Dilophus
tibidis Loew, was taken among sweep-
ings from the high grass along the bor-
ders of Hunter's Creek, at an altitude of