NO. 3 



INSECT HEAD SNODGRASS 



35 



dorsally and laterally is the occipital area. Its anterior limit is de- 

 fined in orthopteroid insects by the occipital suture (ocs). The occip- 

 ital area is subdivided by a suture lying close to its posterior margin, 



Fig. i8. — Generalized structure of the head of an adult pterj-gote insect, 

 diagrammatic. 



A, anterior view. B, lateral. C, posterior. D, ventral. 



a, posterior articulation of mandible ; Ant, antenna ; as, antennal suture ; 

 at, anterior tentorial pit ; c, anterior articulation of mandible with cranium ; 

 CIp, clypeus ; cs, coronal suture; Cv, neck (cervix); cv, cervical sclerite; 

 E, compound eye ; c, articulation of maxilla with postgenal margin of cranium ; 

 /, articulation of labium with postoccipital rim (Poc) of epicranium; For, 

 foramen magnum ; Fr, f rons ; fs, frontal suture ; g, postoccipital condyle for 

 articulation of first cervical sclerite with head ; Ge. gena ; Hphy, hypopharynx ; 

 HS, suspensorium of hypopharynx; Lb, labium; Lin, labrum ; Md, mandible; 

 MdC, opening in head wall where mandible removed; Mth, mouth; Mx, maxilla; 

 MxC, opening in head wall where maxilla removed ; O, ocelli ; Oc, occiput ; os, 

 ocular suture ; ocs, occipital suture ; Pyc, postgena ; Poc, postocciput ; pos, 

 postoccipital suture ; pt, posterior tentorial pit ; sgs, subgenal suture ; SIO, 

 orifice of salivary duct; Vx, vertex. 



here named the postoccipital suture (fig. i8 B, C, pos), which sets ofif a 

 narrow marginal rim of the cranium, or postocciput {Poc), to which 

 the neck membrane is directly attached. The postoccipital suture, 

 though sometimes inconspicuous by reason of the reduction of the 



Mt, 



