﻿164 INTERNAL ANATOMY 



form, the narrow end being posterior, and bulges a little more on one side than upon the 

 other. Passing off from it anteriorly are four coeca, surrounding the oesophagus, and cor- 

 responding to those formed by the apparent division of the ventriculus in the larva ; but 

 they are double the length, and different in form. They are somewhat sacculated ; the 

 two dorsal ones are comparatively narrow and pointed ; the other two have a rounded 

 and dilated extremity. In structure the ventriculus of the pupa is stronger than that of 

 the larva, its muscular tunic being better developed. The coeca are thinner than the ven- 

 triculus. Both of the latter were filled with a white, semifluid substance. The large in- 

 testine differs slightly from that of the larva, except that it is more abruptly dilated about 

 its lower third. The biliary tubes have the same character and relations as in the larva. 



3. Imago. — The oesophagus in the imago has become much elongated ; commen- 

 cing with the same diameter as in the pupa, it very gradually widens, and within the ab- 

 domen dilates into a spacious proventriculus, which extends as far back as the fifth abdom- 

 inal segment. The form of the oesophagus and proventriculus resembles that of a long- 

 necked Florence flask. From the posterior part of the proventriculus, on its dorsal aspect, 

 there projects a short ccecum, which appears to be the remains of the crop of the pupa. 

 In structure the oesophagus and proventriculus are thin, and were generally found much 

 distended with air. The proventriculus joins the ventriculus by a short, narrow tube. 



The ventriculus presents but little variation from that of the pupa ; it is in a more 

 contracted state, and consequently is fusiform in shape, and, from the lengthened oesoph- 

 agus, is placed more posteriorly in the abdomen. The coeca lose the sacculated appear- 

 ance, are all obtuse at the extremity, and are applied to the sides of the proventriculus. 



The large intestine presents a larger convolution than in either of the other stages, 

 is very rugous, the rugse disappearing by inflation ; and it abruptly dilates into an oval 

 or fusiform ccecum in its lower third, which latter opens into the rectum. 



The ccecum is moderately thick and strong, and has developed upon it a double row 

 of glands. Each row, commencing at the posterior part of the ccecum on its dorsal 

 aspect corresponding to each side of the rectum, proceeds forwards to the front of the 

 ccecum and turns down to its ventral surface, and then continues backwards to a point 

 corresponding to their commencement superiorly. The glands are oval in form, white, 

 and placed at pretty uniform distances from each other, beneath the lining membrane of 

 the ccecum and resting upon its muscular and outer tunic. In structure they are com- 

 posed of a layer of simple organic nucleated cells. The ccecum contained the same 

 substance which in the pupa was found in the ventriculus. The rectum comes off from 

 the ccecum opposite the posterior part of the antepenultimate abdominal segment, and 

 proceeds as a narrow canal to the anus. The biliary tubes are the same as in the other 

 stages. 



