ANCESTR Y AND CLA SSIFICA TION. 257 



loop of the other they rest their body, changing 

 the form of the upper arms of the Y from a V to 

 a U. Now when we reach the next family, the 

 typical butterflies, the cocoon, save in the excep- 

 tional instances mentioned, is lost ; while the 

 silken attachments of the chrysalis still remain, 

 modified to suit the circumstances. Instead of 

 the Y-shaped band, wherein to plunge the tail, a 

 carpet of silk is woven upon some branch into the 

 midst of which the hooks are thrust, while the 

 omission of the stem of the other Y leaves a 

 U-shaped loop or girt about the middle. To ac- 

 commodate the chrysalis thus hung next a solid 

 substance, instead of in the middle of an oval 

 cell, the segments of the abdomen must curve up- 

 ward toward the ventral line (for the chrysalis 

 lies back downward), and thus the ventral line 

 becomes straight, while the dorsal is strongly 

 arched [see Fig. 139]. This condition of things is 

 perpetuated and often intensified in the next 

 higher family, the gossamer- winged butterflies, 

 which differ in this respect from the typical but- 

 terflies only in the closer binding of the girt 

 around the middle [see Fig. 58]. In the high- 

 est family, the brush-footed butterflies, the girt 

 around the middle is lost and the chrysalis hangs 

 suspended by the tail alone. We see, therefore, 

 a regular progression from the lower to the higher 

 butterflies, in the loss, first, of the cocoon, next, 



