NO. I 



THE INSECT HEAD — SNODGRASS 



19 



Fig. 7. — Examples of the ecdysial cleavage line on the nymphal and larval head. 



A, Head of an ephemeropterous larva. B, Dytiscus marginalis larva, Coleop- 

 tera. C, Anopheles farauti, Culicidae; head exuviae. D, Chanliodes sp., Megalop- 

 tera, head exuviae. E, Opisthogomphus morrisoni, Odonata, exuviae of head and 

 thorax. F, Magicada septendecim, Homoptera, nymphal head and prothorax. 

 G, Hydrophilus sp., Coleoptera, head of larva. H, Vespula sp., Hymenoptera, 

 head of larva. I, Chalcophora sp., Coleoptera-Buprestidae, head of larva. 



cut out at ecdysis, therefore, cannot be identified as the frons ; it 

 may be termed the cephalic apotome (C, D, Apt). Moreover, the 

 cleavage line does not aWays fork. In some hymenopterous larvae 

 it goes straight dovi^n through the middle of the face (H), and at 

 ecdysis the head cuticle spreads apart in a wide V-shaped opening. 

 Many caterpillars, except at the last ecdysis, shed the head capsule 



