NO. 7 



THE INSECT CRANIUM SNODGRASS 



15 



Fig. 3. — Ephemeroptera, Plecoptera, and Odonata. 



A, ephemeropteron, head of larva. B, Pteronarcys sp., Plecoptera, head of 

 larva. C, Acroneuria sp., Plecoptera, exuviae of head and prothorax. D, Anax 

 Junius (Drury), Odonata, head of larva. E, Opisthogomphus morrisoni Selys., 

 Odonata, exuviae of head and prothorax. F, Archilestes californica McL., 

 Odonata, exuviae of head. 



