62 



THE BIOLOGY OF INSECTS 



Fig. 22. — A, Mandibles and tongue (hypopharynx) of Australian 

 Cockroach {Periplaneta australasiae) , viewed from behind, c, condyle ; 

 g, ginglymus ; mp, molar area ; la, lacinia of mandible. L, adductor 

 muscle ; Ex, abductor ; S, short adductor, hy, hypopharnyx partly 

 turned backwards ; x, y, z, its sclerites {z probably the superlingua or 

 paragnath) ; In, protractor and V, retractor muscle of tongue, ten, 

 tentorium (internal head skeleton) ; rcep, salivary receptacle. X 24. B, 

 The mandibles closed with teeth interlocking. X 15. After J. Mangan 

 {Proc. R. I. Acad, xxvii, 1908). 



