Till-: CIIMYSALIS INTERNAL STRUCTURE. 31 



site sides inclining towards each other at a little more than a right angle. 

 In the V-shaped s[)ace between thcni, and including all the upper domed 

 part of the mesothorax, is the other set, running longitudinally in super- 

 imposed layers. In general the muscles of the abdomen seem to be 

 situated nuich as in the larva, but are more compact and almost or alto- 

 gether longitudinal, tlie oblicjue muscles disappearing. Those of the under 

 surface of the abdomen consist, on each side of the body, of a ribbon, 

 composed of two contiguous strips, the outer slightly the broader, running 

 next the integument through the entire length of the abdomen, the inner 

 edge at about its own width from the nervous cord. 



Digestive system. The oesopliagns is a mere thread-like vessel and 

 runs straight to the stomach ; as it enters the abdomen it is at once directed 

 upward and suddenly expands into a small, bidbous, nuiscular crop, the 

 anterior upper part of which opens into the food-reservoir or paunch, a 

 subfusiform blind sac, broadly rounded at tip, in the nearly adult pupa 

 reaching the extremity of the third or fourth abdominal segment, and lying 

 over the stomach ; in the early stages of the chrysalis it forms with the 

 crop a sim})le minute sac. Directly following this crop, the digestive track 

 widens greatly and forms the stomach, a cylindrical tube, tapering in front, 

 suddenly contracted at its posterior end. It is very large in the young 

 pupa, but gradually contracts, terminating at last near the end of the fifth 

 abdominal segment and only a little beyond the full grown food-reservoir. 

 On each side, at the base, the stomach bears within some rounded lobes, 

 nearly as large as the crop, and besides these, arranged in a row down 

 each side of the median line, it is profusely covered with small pea-like 

 pockets. The intestine in a nearly mature chrysalis is a rather large, cy- 

 lindrical tube, about three times as broad as the oesophagus, slightly tor- 

 tuous, especially anteriorly ; in the mature chrysalis, however, considerable 

 change has been effected, for the intestine has rapidly grown to a much 

 greater length at the expense of its diameter, which is now hardly twice 

 that of the oesophagus ; it is a little larger at the two extremities, but 

 otherwise equal and much more tortuous ; at first it is directed upward, 

 forward, and slightly to one side for a short distance ; then it doubles upon 

 itself, crosses to the opposite side, and moves upward in a tortuous man- 

 ner to the colon, which it enters a little behind and to the left of its anterior 

 extremity. The colon is a small, oval or pyriform sac and gradually passes 

 into the broad straight rectum, which seems only a continuation of it. 



The salivary vessels are composed of slender threads of a uniform size 

 throughout, without any size distinction of duct and gland ; they first run 

 straight beside the slender oesophagus, until near the middle of the meso- 

 thorax, when they take a double turn, and beyond this are at first straight 

 and reach only as far as the stomach ; but afterwards they become very 

 much longer, and instead of being straight form exceedingly fine, crinkled 



