254 THE BUTTERFLIES OF NEW ENGLAND. 



for the median carination, which is distinct througliout but prominent beliind. Edges 

 of wings greatly elevated and thickened throughout. First to the seventh segments of 

 abdomen with a distinct median cai'ina, the prominence of the second segment very 

 high, appressed at base anteriorly, on a side view very strongly arched and very regu- 

 larly rounded, on an end view sloped like the roof of a house, at an angle of about 45°, 

 a little pinched at summit ; eighth abdominal segment having its anterior border a little 

 thickened and raised between the subdorsal regions, and bearing centrally a pair of 

 low, rounded, laterodorsal warts. Preanal button consisting of coarse, grooved, 

 slightly curving, longitudinal, lateroventral ridges, each terminating anteriorly, where 

 they approximate slightly, in a smooth, rounded, anteriorly directed, cylindrical, equal 

 tubercle longer than broad ; the space between the ridges is tumid with a posterior, 

 ventral, linear depression. Cremaster viewed from above very stout, as long as the 

 two previous segments, longer than broad, tapering a little with a lateral and terminal, 

 continuous, coarse, equal, corrugated ridge, those of the two sides parallel ; viewed 

 from the side it is twice as long as broad, nearly equal, expanding a little at the tip; 

 area of hooklets square with lateral prolongations at each corner, longest on the ven- 

 tral ones. Anal hooklets not very long, the basal half straight, the apical curving 

 strongly, bent at right angles but well rounded and enlarging considerably, then 

 diminishing rapidly to a point which is so much curved as to be directed toward the 

 stem. Body transversely and rather delicately striated, distinctly on the third to the 

 seventh aljdominal segments, less distinctly and rather more coarsely on the thoracic 

 segments; basal and terminal abdominal segments, especially the latter, somewhat cor- 

 rugated, the prominence of the second segment principally smooth. 



This genus, including at least five species, is peculiar to North America 

 and occurs everywhere, except south of the United States, on the extreme 

 Pacific slope* and in the furthermost arctic regions. Three or four species 

 occur in the southern half of the continent, another inhabits the north, and 

 one, so far as known, is resti'icted to the Rocky Mountains. One species 

 only is found throughout New England, another in the southern portion, and 

 a third occupies the northern half or more. On the extreme Pacific coast, 

 as in Europe, the group is almost everywhere replaced by the very closely 

 allied genus Najas. 



The butterflies of Basilarchia are moderately large in size and differ 

 greatly in appearance, since two species, or even three, according to Double- 

 day and Wallace, mimic in attire butterflies of very different groups ; but 

 in all their earlier stages the three New England species resemble each 

 other so intimately that even one well acquainted Avith them can with diffi- 

 culty distinguish the separate forms. Owing to this great variety among 

 the butterflies it is difficult to give any general description of their colora- 

 tional pattern ; but the normal types are a deep, dark, rich purple or blue 

 black, with a very broad, common, extra-mesial white band, broken by 

 dark nervules, and followed exteriorly on the hind and sometimes also on 

 the front wings by small reddish spots, and these again by a common sub- 

 marginal series of pale bluish or wliitish lunules or spots — all the marginal 

 markings being larger beneath than above ; midway between the extra- 

 mesial band and the apex of the fore wings is a second short, transverse 



* One species reaches it near our northern boundary, 



