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Psyche 11:1-6, 1904.

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PROBLEMS IN THE GENUS BASILARCHIA. PLATES 1-111. \ BY W. L. W. FIELD, MILTON, MASS.
Among the representatives of the genus Bas/'/arc/;ia occurring in the north- --
eastern United States are certain remarkable forms which seem in a measure to bridge the gaps between the three types to which specific rank has been generally accorded. Some of these intermediate forms have been figured and described as probable hybrids, others as aberrant or dimorphic forms; several others are known to which no distinct names have been given. This paper is the result of an effort to summarize the existing knowledge of these forms, in order to prepare the way for methodical investigation.
No attempt will be made here to present detailed descriptions of these familiar butterflies, which are treated in ail the leading works on North American . . lepidop tera.
It will suffice to point out certain pertinent facts. I.
B. arthemis Drury (Plate I., fig. 5, <; ; Plate II., fig. 4. $ ) , the common white-banded species of the inountai ti districts, ranges very widely through Canada, and in Lhe United States frequents northern New England, the Adirondack and Catskill regions, and a belt of country extending westward to Minnesota. About Boston it is very rare, bu~ has been taken by Harris, Clapp, Miss Guild, Morse, F. H, Sprague, P. S. Sprague, Zerrahn and others. Reported instances of its capture south of the latitude of Itoston are so scarce as to emphasize its almost complete restriction to the hilly country of the north. The species is reported from most stations either as single-brooded or as having a partial second brood. .
-..
The larvae feed upon poplar and willow,
2.
B. astymwx Fab.
(Plate I., Kg. i, J ; fig. 2, 9 ), the blue-black species without white band, is absent, from Canada with the exception of southern Ontario. and even in the United States encroaches very little upon the territory of trrtftemis. In general it may be said that as/stz~ax seldom appears north of latitude 43", but that south of latitude 42' it replaces arthe~~iis. It is found as far west as the



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Mississippi.
About Boston it is much more common than arthfmh. The larvae feed upon apple, willow, puplar, and 4 d cherry. Astymax is generally double-brooded, though at some points near its northern limit the second brood is only a partial one. This species is extremely variable
both h size and markings.
Very large examples, rivailing Semzopsyche diaita in size; occur from ??ew York city southward: and mingling with these are found spechs scarcely larger than the average (trthet)tis. Both sexes attain to both extremes of size, though the larger specimens are usually females. 3.
B. arck;/pus Crarner, "the Viceroy " (Plate II., fig. I, ; Plate I, fig. 6, 9), is the most famous example of mimicry among North American butterflies. The mimicked species is Anosia plexippus, the Monarch or Milkweed butterfly. Arehippus has, instead of the deep brown or blue-black ground color characteristic of the Sasilwchias, the orange coloring of Aftosia. Unlike its allies, but like Aaosia, it frequents sunny open fields, and in such situations may be found throughout the eastern United States. It is triple-brooded throughout almost its entire range. The larvae feed upon several species of willow, and sometimes on poplar.
ArtAipf>us is extremely variable in size, like astyanax. The depth of the - -
ground color also varies somewhat, and the mesial black tine of the secondaries is often (more frequently in females) indistinct or incomplete. The incomplete con-
dition is to be seen in the female here figured1 . .
1. Basilanhia poserpinu Edwards, the first of the forms to attract attention, was described in 1865 from two males taken in the Catskill moun- + tains, and redescribed later (Edwards '67, '69) when the same region yielded more material. The following is quoted from the notes accompanying the second ( '67) description :
On the same day 1 took about fifty Arfk̤mis all except two or three being males. ant! just from chrysalis. I have never known ArtAemis so abundant in that locality. The variil- Uon among so many was remarkable, particularly in the width of the whita band and the size of the russet spots above and below ; in half the specimiens these spots were wanting above, In others there were two or three and from that up to a complete series of large rounded spots; the color of under side ran through all shades, from blackish to brown, cinnamon and russet.
Notwithstanding Ins observations upon these intergrading forms, all of which he referred to artht~~~is, Edwards for some time believed pmerpina to be a distinct



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[February
The larvae
:s northern
:ly variable
e &am in
are found
in to both
'late I, fig.
butterflies.
I butterfly.
yracteristic
3, but like
be found
almost its
netimes on
pth of the
ondaries is
-J
nplete con-
: forms to
skill moun-
Ided more
cond ( '67)
males, and
The varia-
and the size
iting above,
-ge rounded
I, cinnamon
II of which
! a distinct
Ìà
species.
Scudder ('72) treated it as a variety of astyanax, and in ctiticising this view Edwards ( '73) suggested that it might be a dimorphic form of arthemis. The discovery of "other varieties of fmctpifta ?' led Scudder ( '75) to adopt this view tentatively, though he suggested thatproserpina might prove to be a hvbrid between - .
arfhemtf and as/vanax.
Two years later Edwards ('77) announced the rearing of larvae from eggs laid by a captured pwerpina ; * four came to maturity, giving three typical urtftemis (or form htina, as he then designated it) and one proscrpina closely resembling aslyanax.^ After another space of two years, Edwards ('79) published a full account of his studies of proserpim, including an exhaustive list of localities in which it had been taken, and a history of the breeding experiments. On the plate accompanying this was figured a " variety " of proser#i~m, the oftquoted specimen from Mr. Mead's collection.3 This will be referred to later. One of the most noteworthy features of $roserpina is its distribution, which is almost wholly confined to the narrow zone in which the ranges of arihewtis and astyanm overlap.
2. B. artkechippus Scudder, (Plate II., figs, 2, 3), generally regarded as a hybrid between arthemis and archip/us, was described from a specimen taken at Chateauguay Basin, Quebec, in 1879, by Mr. J. G. Jack.' The specimens here figured were taken in Alstead, N. H., .by the Field brothers, in 1895 and 1896 ; still another was seen on the wing in the same locality in 1902, but not captured. The three above mentioned are now in the Museum of Comparative Zoology.
Arthecfttppus exhibits a very thorough mingling of the characters of its sup- posed parents, and the three specimens preserved are almost exactly alike in appearance. All three are males; whether females ever occur remains to be seen. 3. An unnamed Basilarrhia, apparently a hybrid between astymx and acrehippus, is represented by fig. 4 on Plate I. This specimen was obtained by Mr.
'
A, P. Morse from Sherborn, Mass., and is a male. The ground color is mahogany
brown; the spots of the inner row are deep orange, those of the outer row some- what paler.
There are no blue markings.
Mr. Jacob Doll has a similar specimen which was taken on LO& Island, and one or two others have been reported.
1% Bile whih luid impregnated tha f d e wai d taunc unknown. ' B a d - = win Fab.
Edward* employs the litter name.
'This "itrietyVhas also been figurtd by Scuddtr fXnl and Holdad ('qqj, the latter failing to mtadoa the fact that it il cat a tyflialffruur/'fw. Theiptrimcn reproduced herewith u hg. 6 on Plus lit. nstmblta it cl̤cly but Lyiui some at the red markings.
'ScuiiderfSftt and Scudder had
1 the same specimtt.




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Sf.* W"U. r'*'.*- -- .. 0'
typical adem&. Red spots appear on upper surface of secondaries as in most specimens of arthemis. Figured (Plate III., fig 5) from a male taken in Temple, N. H.
(d) A form resembling tistyittax (ursdi) in many ways, yet having the white band well developed on aH the wings. The blue scales on the upper surface of secondaries are abundant and brilliant. This form is called by some collectors a. 'whitebanded mla." A small specimen of this form, reared at Sharon, Mass., fmrn a hibernating larva by Mr. A. C. Sampson, is fgured as fig. 6 on Plate TTT1 Very large specimens, taken on Long Island, are in the collections of Messrs. Jacob Doll and H- H. Xewcomb. There are two specimens in the Museum of Compara- tive Zoology; one of these is front Deerfield, Mass., and the other bears no locality label. The spimen from the Mead coliection is similar to these, but shows more red on the upper surface.
ST^ tpfd- now in Mr. Newcomb's collcclion. ,



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id which by
fore treated
un the hta
with being
mpt a corn-
but it seems
size is that
mid white
i somewhat
id the blue
rds in 1868
ales of this
w the under
ut one-third
r dark as in
Female from
ind appears
he band on.
1 as in most
in Temple,
the white
r surface of
dlectors a
iron, Mass.,
Plate IIX1
essrs. Jacob
t Compara-
t no locality
but shows
Scudder (39) treats proserpina as a hybrid produced by the crossing of artkernis and astymtax. The principal facts upon which he bases his theory are : I. The occurrence of apparent hybrids arthemis-archippus and asfyanax- ofthiffus.
2.
Proserpina resembles astyanax even more closely than arthemis, to which latter species Edwards has proved it to be in some way related. 3. In structure of genitalia proser/h and asfpnax are precisely alike. Prese+inft is more variable than either of the supposed parents, 5. Prgserfiivw occurs only in a narrow belt where the ranges of its supposed parents overlap.
6.
"Prow--ha is known at so many points in this belt, that it presumably occurs wherever arthemis and astyanax are brought into contact." 7. No dimorphic species is known of which one of the forms appears only along one edge of the territory occupied by the species. The three recognized species, Sasii'arcfucs arthemis, B. astyanax and E. arch$- fus, all occur together in a narrow zone running westward from the Atlantic coast to the Mississippi river ; north of that zone, arthemis and archippus occur together ; south of it, asfyaftax and arcA'/p//s occur together. With these three species we may effect three different combinations of two species each, vix.: arkhemis-arcft///us, arthemis-ustyansx, arch If/tts-astyimax. Each of these three combinations is actually represented by an intermediate form.
Two of these intermediate forms, arthgmis-arch'/pus and archÌö//us-asiyamx are generally believed to be hybrids, but their hybrid nature is as yet undemon- stratcd.
The third, arfhemis-asiyanax, is really a group of several interblending forms, assembled under the name poserpinu.
The proserpim forms are either the results of the intercrossing of arthewis and astyanax, or polymorphic forms of arthtd They are found in the narrow zone -
above mentioned.




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6 PSYCHE
[February
VII. CONCLUSION.
The futility of speculation and the importance of actual experiment are well shown in the cases presented.
The problen~s involved in the inter-relations of these butterflies are of interest to all biologists. They can only be solved by
careful and long-continued investigation. At the Alstead laboratory the effort will be made during the coming summer to breed hybrid Basilarchias in a large enclosure, with growing trees on which the larvae may feed. Quantitative studies of variation in this genus are now under way. It is hoped that before the close of the summer new light may be had upon the questions here discussed.
I am indebted to Messrs. A. P. Morse, H. H. Newcomb and A. C. Sampson for the loan of specimens from their collections. a
BIBLIOGRAPHY.
EDWARDS, W. H.
1865.
Proc. Ent. SOC. Phila., 1865, p. 148.
1867. Trans. Am. Ent. Soc., I., 286.
1869. Butterfiics of Xorth America. I., Limenitis I. Boston and New York. 1873. Can. Ent., V., 232.
1877. Can. Ent., IX., 114.
x8n.
Butterflies of North America, II.. Limenitis I. Boston and New York.
GREY, R. 31.
1879. Can. Ent., XI., 16.
HOLLAND, W. J.
fw. The Butterfly Book. New York.
%UDDER, S. H.
1872. Syst. rev. Am. buttertiies. Rep. Peabody Acad. Science. 1.875.
Bull- Buffalo Soc. Sat. Sc., II., 349.
1889. The Butterflies of the Eastern United States and Canada, with specia1:referente to New England. Cambridge.
STRECKER. H.
1378. Butterflies and Moths of North America. Diurnes. Reading, Pa.



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