hosford: head segmentation of insects. 71 



that much stress should be laid on this supposed homology. 

 I, myself, do not think the evidence brought forward on this 

 point is very conclusive. 



Pleural sclerites. — Postgense. A suture which is the more or 

 less open mouth of an apodeme divides the postgense as does 

 the apodeme the pleurites of the thoracic segments. The man- 

 dibles, like the coxse of the legs, fit into the openings where 

 the apodemes begin. 



The antecoxal pieces. In Gryllus and the larvse of Corydalis 

 the mandibles articulate with a sclerite distinct from the 

 clypeus. This corresponds to the antecoxal piece in the tho- 

 racic segments. 



Appendages. — Mandible and trochantin, a small sclerite at 

 base of mandible in Orthoptera and Amblychila. 



5. Superlingual. 



Tergal sclerites. — None found. 



Sternal sclerites. — Represented by that part of the floor of 

 the mouth cavity which bears the superlinguse. 



Pleural sclerites. — Represented by that part of the floor of 

 the mouth cavity which bears the superlinguse. 



Appendages. — Superlinguse. 



6. Maxillary. 



Tergal sclerites. — None found. 



Sternal sclerites. — Lingua. This is the unpaired portion of 

 the hypopharynx, and evidently pertains to the sternite of this 

 segment, because it arises between the rudiments of the 

 maxillse. 



Pleural sclerites. — Maxillary pleurites. There is a narrow 

 band or sclerite that runs around the posterior margin of the 

 epicranium. This is the posterior pleurite. The anterior one 

 is scarcely visible except in a few insects, as in the cockroach 

 and cricket. Between these two sclerites is an apodeme, which 

 forms the posterior arm of the tentorium. In Amblychila this 

 apodeme and the two sclerites are very clearly seen. 



Appendages. — Maxillse. 



a-Univ. Sci. Bull.. Vol. VIII. No. 2. 



