Studies on Life-history of Bomhycine Moths. 49 



3. But the most striking adaptive features are : {a) the peculiar 

 shape of the head, and also (6) of the suranal plate, both being 

 steeply inclined planes, and both serving as stoppers to close each 

 end of the case ; both being broad, rounded, and the surface not 

 only sloping, but also so colored as to cause it to be easily con- 

 founded by the observer w^ith the exterior of the sack. This is an 

 adaptation in direct relation to the form of its case, and must have 

 been due to the transmission of acquired characters during the life- 

 time of its ancestors, after they had begun to construct cases. 



4. The body so flattened that the spiracles can be seen from above. 

 Its case is not so regular in form as that of Perophora ; it is 



quite irregular on the edges, the midrib on one side projecting in 

 front and behind ; it is about an inch long and three-quarters of an 

 inch wide. 



Full-grown larva — Length 25 mm. (one inch). The head and 

 body are somewhat flattened, so that the spiracles can be seen from 

 above. The head is large, broad, and flattened, the dorsal surface 

 forming a rather steeply inclined plane, like that formed by the 

 dorsal surface of the suranal plate. The surface of the head is 

 rough and corrugated. It is pale yellowish clay-brown (luteous), 

 mottled with dark brown on the side; but in the middle and in 

 front dark brown. The mandibles are dark brown, very solid and 

 thick at the end. The antennae are normal. There are no traces 

 of the remarkable bulbous appendages characteristic of Perophora. 

 The labrum is dark brown. The head is as wide as the prothoracic 

 segment, which is narrower than the rest of the body. The 2d and 

 3d thoracic segments increase in breadth, while the body is thickest 

 just behind the middle, not decreasing in width until the 8th seg- 

 ment. The end of the body is broad and rounded. The suranal 

 plate is large, broad, and well rounded behind; with the surface 

 slightly convex and considerably inclined so as to form a close 

 stopper for the posterior opening of the case; on the dorsal surface 

 are two quadrant-shaped rough semi-chitinous pale, parchment-like 

 areas, provided with a few whitish hairs arising from minute warts. 



The body is smooth, nearly hairless, the minute setae being short, 

 erect, blunt at the end, the two largest ones being situated on the 9th 

 abdominal segment. The body is flesh-colored above and slightly 

 luteous or clay-yellow on the sides; the body in my s|)ecimen was 

 not quite so dark as Riley describes. The spiracles are couspicuous, 

 black-brown, pale in the middle. The dorsal surface of the pro- 



