NO. 3 



INSECT HEAD SNODGRASS 



143 



separated from the neck. A large suljniental plate occupies the median 

 basal part of the submental region in some species (A, Smt). 



The distal, free lobe of the labium probably represents the mentum 

 and ligula of other biting insects, combined with the hypopharynx, 

 which forms its anterior surface (fig. 54 A). Evidence of this in- 

 terpretation is found in the fact that the labial and hypopharyngeal 



Hphy, 



SID 



-- Pr 



Hphy 



Fig. 54. — Distal part of labium, hypopharynx, and silk press of a noctuid 

 caterpillar. 



A, mentum and hypopharynx, with silk press partly exposed, lateral view. 

 B, the same, dorsal view. C, the same, posterior view, showing support on arms 

 of stipites iq, q). D, lateral view, showing muscle attachments. 



Hphy, hypopharynx ; Mt, mentum ; Pr, silk press ; q, q, ridges of stipes ; r, r, 

 articular nodules between stipital arms and mentum ; SID, silk duct ; Spt, 

 spinneret. 



muscles are inserted on the base of the lobe (figs. 53 C, D, 54 C, D, 

 15, 16), and in the position of the spinneret (fig. 54 A, D, Spt), which 

 contains the opening of the silk duct (salivary duct), the latter being 

 normally situated between the labium and the hypopharynx (fig. 18 

 D, SIO). 



The mental region of the mento-hypopharyngeal lobe appears to 

 be that occupied by the large proximal plate (fig. 53 A, Mt) that em- 

 10 



