TRANSFORMATIONS OF EUSLEUS ATALA. 417 



scarcely larger than the succeeding ; the terminal segments are distinct and uniform in size 

 as in caterpillars of other families, the terminal segments not depressed, and the spiracles 

 of the eighth abdominal segment on a line with the others. AH the spiracles, however, are 

 situated high up upon the body as m the other members of this sub-family, so that the lat- 

 eral row of fleshy, thorn-bearing tubercles, which, in most other caterpillars, would be supra- 

 stigmatal, or situated even relatively higher on the sides, are here ventro-stigmatal ; and the 

 upper similar sei'ies, which, like that previously mentioned, extends along the whole length 

 of the body, is pleural when it appears to be jileuro-dorsal (fig. 4); each of these rounded 

 elevations bears a number of pretty long, slender, tapering thorns, and the whole body is 

 covered with minuter ones ; the posterior segment is fringed with a bristling mass of thorns 

 similar to those on the tubercles, and the first thoracic segment where it is thickened above 

 the head, is similarly though not so heavily armed. The head is smooth, well rounded and 

 compact, about two-thirds the width of the first thoracic segment. The legs are small and 

 bear a very delicate claw. The prolegs are provided with a double interior series of about 

 fourteen hooked spines each, alternately long and short ; the anal prolegs are particularly 

 well developed, being scarcely shorter than in the Papilionides. 



In the characteristics of the caterpillar at this stage therefore, Eumasus departs widely 

 from the ordinary type of Ephori, whose caterpillars are decidedly onisciform with excess- 

 ively short though perfectly developed legs and prolegs, a minute head wholly retractile 

 within the greatly developed first thoracic segment, the terminal segments more or less 

 coalesced and the spiracles of the eighth abdominal segment situated above the line upon 

 which the others are ranged. When, however, we come to the final stage of Eumoeus 

 (figs. 6-9), we find the thoracic segment slightly enlarged, tumid and overhanging the head 

 (figs. 6, 9), the whole ventral portion of the body flattened, and the dorsal portion arched, 

 with ridges running along pleural and ventro-stigmatal lines accentuated by the fleshy 

 tubercles still situated there, the terminal segments coalesced to a slight degree, and flat- 

 tened so as to bear a close resemblance to those of the lower Ephori. The spiracles, how- 

 ever, are still in a straight line, and although the segments are transversely ridged on 

 their posterior border, apparently by a contraction of the mass in this quarter (fig. 7), the 

 animal is still of unusual length and slenderness for one of this family. So, too, the head 

 is still only partially retractile within the first thoracic segment, and the anal prolegs are 

 pretty well developed. 



These characteristics wherein the larva of Eumfeus differs from the generality of Ephori 

 are the very ones wherein it is alhed to the Vestales, and shows the correctness of West- 

 wood's arrangement of the genus and of the conclusions to which we have already arrived. 

 Very few larvae of Vestales are known, and those with which we are acquainted differ 

 considerably among themselves ; they are, however, not always so strikingly onisciform as 

 are the Ephori and are sometimes furnished with tufts of short hairs or lateral fleshy 

 appendages, and even, on the first thoracic segment, with long spines; the first segment 

 of the body is not enormously developed, nor, apparently, is the head retractile, at least to 

 the extent that it is in the Ephori. The larva of Ancyluris Ilelibceics is described as 

 furnished with tubercl.es or solid points of unequal length placed in two rows on either side 

 of the body ; and as, in general, resembling the caterpillar of Liparis. It would seem to be 

 not unlike that of the penultimate stages of Eumasus. 



Eumseus therefore, judging from the larva, is one of the Ephori which approaches the 



MEMOIRS BOST. SOC. NAT. HIST. VOL. H. 105 



