154 CALIFORNIA ACADEMY OF SCIENCES. 



the Amblycera, the second to the Ischnocera, Of the 

 first, the alimentary canal of Menopon titan (plate xi, 

 fig. 13, plate X, fig. 1, and plate xvii, fig. 6) may be 

 taken as an example. It has the form of an almost 

 straight tube separable into six distinct parts. The first 

 of these is a narrow elongated buccal cavity (plate x, 

 fig. 1, 6c) extending upward and backward from the oval 

 aperture, by which it opens anteriorly, to the second 

 part of the alimentary canal, the pharynx (p). This 

 is a large cavity, oval in longitudinal sections, having its 

 long axis extending backward and upward, but not so 

 much in the latter direction as that of the buccal 

 cavitv, so that the two form an ang-le with each other. 

 The pharynx lies mostly in front of the brain . (6) 

 and suboesophageal ganglion (s.re. g.)^ the commisures 

 lying laterad of its posterior end. Between the latter 

 the pharynx contracts and passes into the oesophagus. 

 This is rather long, narrow, gradually expands pos- 

 teriorly, passes uninterruptedly into the crop, and 

 forms with the latter the third division of the alimen- 

 tary canal {ce and cr) . The crop is of variable size 

 according to the contents, but is rather large when dis- 

 tended. 



The fourth part, the ventriculus, is long, wide in 

 front and narrow behind, and connected with the crop 

 in front by a short, very narrow neck. On each side of 

 this it is produced into a large ctecum, the two embrac- 

 ing the posterior end of the crop. Back of the 

 stomach is the intestine forming the fifth and sixth 

 divisions of the alimentary tract. The first of these two 

 consists of the prerectal part of the intestine and the 

 second of rectum. The former is a short, straight, 

 narrow tube, a little enlarged toward the middle and 

 separated from the ventriculus in front and the rectum 



