284 Annals Entomological Society of America 'V i". XI, 



the buccal'cavity, then the pharynx (the hmits of which are de- 

 termined by the attachment of the muscles which run from 

 the ahmentary canal to the body wall), and third, a short, 

 narrow^ muscular oesophagus which extends as far as the 

 prothorax, where it gradually broadens out into a thin-walled 

 distensible crop, the fourth division, the diameter of which is 

 half as great as that of the mesenteron. A constriction, as well 

 as a conspicuous difference in the thickness of the walls, marks 

 externally the separation between the fore-intestine and the 

 mid-intestine. 



The mid-intestine composes by far the largest part of the 

 digestive tract of this species. The ventriculus runs through 

 the body as a straight tube of nearly uniform diameter, from 

 a point near the beginning of the mesothorax to the end of the 

 fourth abdominal segment, where a slight constriction is appar- 

 ent ; from here on it is somewhat convoluted and of less diameter, 

 extending nearly or quite to the end of the seventh abdominal 

 segment. Correlated with this macroscopic division into the 

 two sections, is a differentiation of the lining epithelium. 



The hind-intestine, which is composed of three regions, 

 begins in the posterior portion of the seventh abdominal seg- 

 ment, where it joins the mid-intestine at a sharp angle. The 

 six Malpighian vessels arise at the point of union' Their 

 origin and distribution has already been discussed (Woods 

 1916). They are divisible into two series, the first (i. e., 

 posterior) consisting of four vessels, and the second (i. e., 

 anterior), of two. The vessels of the second series arise as 

 separate evaginations from the intestine at the point where the 

 mid-intestinal epithelium passes into that of the hind-intestine. 

 The vessels of the first series unite into a bladder, which opens 

 directly (i. e., without a stalk or urethra) into the lumen of 

 the ileum (first division of the hind-intestine), slightly posterior 

 to the evagination of the tubes of the second series. After a 

 greater or less course through the body-cavity, the vessels of 

 the first series unite into two pairs, and to each ])air is joined 

 one of the vessels of the second series, so that two common 

 trunks of three vessels each are formed. These trunks pass 

 into the wall of the colon (second division), where they end 

 blindly in irregular ramifications. 



At the junction of the mid-intestine with the hind-in:estine, 

 there is a sharp turn in the alimentary canal, so that, i:ie:ween 



