52 



Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



Neureclipsis, Plectrocnemia, Polycentropus, 

 Holocentropus, Nyctiophylax and Cyrnellus. 

 An interesting link between the two groups, 

 Cernotina, was recently described. 



KEY TO GENERA 



Larvae 



1. Anal hooks with a row of 4 or 5 long 

 teeth along inner ventral margin, 



fig. 189; tenth segment short, with 

 scarcely any ventral margin, fig. 191; 

 mentum forming a pair of distinct, 



sclerotized plates, fig. 194 



Psychomyia, p. 75 



Anal hooks with at most very short, 

 inner teeth, fig. 190; tenth segment 

 longer and tubular, figs. 192, 193; 

 mentum not divided into two scle- 

 rotized plates, fig. 195 2 



2. Mandibles short and triangular, each 



194 



195 



198 



Fig. 189. — Psychomyia flavida larva, anal 

 hook. 



Fig. 190. — Psychomyiid Genus A larva, anal 

 hook. 



Fig. 191. — Psychomyia flavida larva, apex 

 of abdomen. 



Fig. 192. — Neureclipsis crepuscularis larva, 

 apex of abdomen. 



Fig. 193. — Polycentropus interruptus larva, 

 apex of abdomen. 



Fig. 194. — Psychomyia flavida larva, head, 

 ventral aspect; w, mentum; sm, submentum. 



Fig. 195. — Polycentropus interruptus larva. 



200 



head, ventral aspect; m, mentum; sm, submen- 

 tum. 



Fig. 196. — Phylocentropus placidus larva, 

 mandibles. (After Vorhies.) 



Fig. 197. — Neureclipsis crepuscularis larva, 

 mandibles. 



Fig. 198. — Polycentropus interruptus larva, 

 mandibles. 



Fig. 199. — Psychomyiid Genus A, mandibles. 



Fig. 200. — Psychomyiid Genus B, venter of 

 ninth and tenth segments. 



Fig. 201. — Psychomyiid Genus B, apex of 

 abdomen. 



