NO. 3 



INSECT HEAD SNODGRASS 



141 



Fig. 53. — Maxilla, labium, and silk press of a caterpillar. 



A, Estiijmenc acraca, maxillae and labium, with hypostomal plates of head, 

 posterior (ventral) view. B, internal view of left maxilla and hypostomal 

 region of same, showing muscles. C, Malacosoma americana, distal part of 

 labium and hypopharynx, lateral view, showing silk press and muscles. D. 

 Lycophotia mar g aril osa, muscles of maxillae, labium, and hypopharynx, internal 

 (dorsal) view. E, the same, right side of head, internal view, showing muscles 

 of labrum, mandible, maxilla, and labium. F, cardo and lateral parts of stipes 

 of right maxilla, showing bases of muscles, dorsal (anterior) view. (Compare 

 with E.) 



a, anterior articulation of mandible; AT, anterior arm of tentorium; Cd, 

 cardo ; Clp, clypeus ; dap, dorsal apodeme of postoccipital ridge ; c, articulation 

 of cardo with cranium; Fr. f rons ; /;, submarginal ridge ot clyjeus : Hpliy. 

 hypopharynx ; Hst, hypostoma ; /, hypostomal suture ; k, accessory plates of 

 cardo; l, basal sclerite of lacinia ; Lc, lacinia ; Lm, labrum; Md, mandible; Mt, 

 mentum; NMb, neck membrane; PT, posterior tentorial arm; pt, posterior 

 tentorial pit ; q, ridge on inner edge of stipes ; r, articular nodule between 

 end of stipital ridge (q) and mentum; SID. silk gland ducts; Suit, submentum ; 

 Spf, spinneret; St, stipes; Tut. transverse bar of tentorium; vap, ventral apodeme 

 of postoccipital ridge. 



