8o 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



THE ALIMENTARY CANAL 



The alimentary canal (fig. 39) of the larva shows some of the more 

 primitive conditions of the highly specialized digestive system of the 

 adult. It is about i^ times as long as the body. The same chief divi- 

 sions as in the adult stage are clearly defined, but the proportions of the 

 length of these are quite dififerent. The fore-intestine occupies only 

 one-ninth of the whole alimentary canal while the mid-intestine is 



Fig. 39. — Gnathotrichus inatcriarius Fitch: Alimentary canal and its appendages 



of a full-grown larva. 



A, fore intestine; B, mid-intestine; C, hind intestine; Mai', malpighian vessels; Oes, 

 oesophagus; Re, rectum; I'e. ventriculus; a, region corresponding to crop and proventriculus; 

 b, posterior tuIie of mid-intestine; c, large intestine; d, small intestine; e, reproductive canal. 



enlarged to spread over five-ninths of the same length. The gastric 

 coeca are small, the proventriculus absent and the Malpighian ves- 

 sels are very strongly developed. 



Fare-intestine. — The epipharynx (fig. 38, Eph) is well developed 

 and projects distally slightly over the anterior margin of the labrum. 

 It is distinctly defined from the labrum and clypeus ; four papillae occur 

 anteriorly and a row of sensory pores medially. The latter punctures 

 are reduced to a single puncture in Ch. vest it us and are absent in Den- 

 droctonus valeiis. according to the respective authors. The hypo- 

 pharynx does not show any armature or sensory organs. 



