138 PROC. EXT. SOC. WASH., VOL. 21, NO. 6, JUNE, 1919 



"pc" analogous to, if not actually homologous with, the similar 

 posterior horn of the wood-boring larva of the Coleopteron 

 Cupes, etc., although it is not exactly comparable to the caudal 

 horn of the lepidopterous sphingid larvae. Above, and to one 

 side of the post cornus, "pc," of Figs. 47 and 48, is a lateral caudal 

 groove "Ig," and above the base of the postcornus is a dorso- 

 median caudal groove "dg" exactly similar in both larvae; but 

 in Tremex (Fig. 47) a pair of cornicles "c" probably homologous 

 with the cerci (although the homologies of similar cornicles of 

 coleopterous larvae with cerci of lower insects have been dis- 

 puted) is situated near the end of the dorsomedian caudal groove 

 "dg" not far from the base of the postcornus "pc," while in Cephus 

 (Fig. 48) these cerci are lacking. On the other hand, the ventral 

 plate "hy" situated below the anal opening "a" of Cephus (Fig. 

 48), bears a pair of appendages labeled "s" which cannot be 

 homologized with the cornicles "c" of the similar larva of Tremex 

 (Fig. 47) since they do not occupy the same position in the two 

 larvae with respect to such "landmarks" as the dorsomedian 

 cuadal groove "dg," lateral groove "Ig," postcornus "pc," anal 

 opening "a," and ventral region "hy," which are practically 

 the same in both larvae (Figs. 47 and 48). The ventral append- 

 ages "s" of the larva of Cephus (Fig. 48), however, occupy a simi- 

 lar position with respect to the anal opening "a," ventral region 

 "hy," etc., as the structures "s" of the larva of Neurotoma (Fig. 

 44) do, and there can be little doubt that the structures labeled 

 "s" are homologous in the two larvae shown in Figs. 48 and 44. 

 If the cornicles "c" of the larva shown in Fig. 47 are cerci (the 

 designation "anal" cerci is not necessary, since the term cerci 

 alone sufficiently defines the structures in question), then the 

 structures labeled "s" in Figs. 48 and 44 are not cerci, and it 

 would be incorrect to designate them as such (as is done by Mac- 

 Gillivray, 1913, who calls them all "anal cerci") and the term 

 arthrostyli, or segmented styli should be applied to the append- 

 ages "s" of Fig. 44, since they are apparently homologous with 

 the arthrostyli "s" of the ephemerids, etc. (Fig. 58). 



The half English, half Latin designation "prolegs" is usually 

 applied to the abdominal limbs of larvae; but if the terms prono- 

 tum, procoxae, protarsus, etc., indicate structures of the pro- 

 thorax, then the term "prolegs" should refer to the legs of the 

 prothorax alone, and in the interest of exact usage the designa- 

 tion uropoda (which according to Smith's "Glossary" refers to 

 the abdominal legs in general) should be applied to the limbs 

 of the urites as the abdominal segments are commonly called 

 among entomologists. Most recent investigators now admit 

 that the abdominal appendages in question represent the vestiges 

 of true limbs, so that there can be no objection to calling them 



