101] LEPIDOPTEROUS LARVAE — FR ACKER 101 



legs of any of its members reduced to two pairs, one ventral and one 

 anal, no difficulty need be encountered in placing the great majority of 

 the species in the proper family. The additional rudimentary prolegs 

 of Brephos, Anisopteryx, and a few other genera are likely to cause 

 confusion. The larvae of this family are distinguished by the following 

 characters, some of them possessed by other families, but when taken 

 together, completely diagnostic of the Geometridae. 



Body usually slender and cylindrical but sometimes bearing humps, 

 processes, and protuberances of various kinds and shapes ; only primary 

 setae present above the level of the spiracle, but below eta subprimaries 

 always found, varying in number from one, lambda, to many, covering 

 the lateral half of the proleg. Prolegs of abdominal segments 3, 4, 

 and 5 absent or, in a few cases, rudimentary; crochets biordinal, ar- 

 ranged in a mesoseries. (Fig. 63.) 



Family Platypterygidae. 



Head about as high as wide, obscurely bigibbous ; no secondary setae 

 present. Prothorax with epsilon and rho much farther cephalad than in 

 most Macrolepidoptera, Kappa group consisting of two setae. Pi group 

 usually consisting of several setae borne on a lateral fleshy protuberance ; 

 mesothorax with all setae above spiracular level normal ; below eta five 

 or six setae are present in various arrangements, usually two on a level 

 with mu of the abdomen and several in a group at the base of the leg 

 forming the Pi group ; metathorax similar. Abdomen with alpha and 

 beta separate, epsilon and rho separate dorsad of spiracle, kappa cau- 

 dad of spiracle, and eta below ; mu present ; three setae at base of pro- 

 leg and three more on its lateral surface ; segment 9 various. Setae 

 usually borne on small chalazae, with great variation on ventral half of 

 body, tho never very numerous. Prolegs of segments 3 to 6 with the 

 planta circular, the crochets biordinal or uniordinal, arranged in a 

 pseiidocircle (Fig. 97), with the mesoseries extending about half way 

 round the proleg, the lateral series shorter, with smaller crochets, not 

 continuous with the mesoseries; anal prolegs wanting. Suranal plate 

 terminating in an acute process (Fig. 89). Spiracles elliptical, those of 

 prothorax about twice as large as those of abdominal segments. 



The genera, representatives of all four of which are in the U. S. 

 National Museum, may be distinguished by the various shapes and sizes 

 of the processes bearing the setae. 



Eudeilinea. Metathorax cylindrical, smooth above ; head not 

 bicornute ; crochets uniordinal. The family Auzatidae, including in 

 America only the single species of this genus, E. herminiata, is consid- 

 ered distinct from Platypterygidae in Comstock's "Manual for the 

 Study of Insects." The absence of a chalaza from the metathorax of 



