154 MR. p. OHAXMBES MITCnEI,!. ON THE [Jan. 14, 



gut as a simple derivative of the type seen in Pterocles. The duo- 

 denum is longer and narrower. The circular loop is enormously 

 expanded, but the three subsidiary loops seen in Pterocles remain. 

 The first of these is somewhat shortened ; the second, that bearing 

 the yolk-sac vestige at its end, is enormously lengthened ; the mesen- 

 tery is folded along the line of tlie median mesenteric vessel, so 

 that the two limbs of the loop are brought in contact with each 

 other, and, finally, the whole folded loop is rolled into a rough 

 spiral. The third subsidiary loop of the circular part of the gut 

 has the same arrangement and veins as in Pterocles; but thecseca 

 no longer run along it, but occur as very short stumps upon the 

 rectum. 



CuOULirOUMES. 



Of these, I have examined only OorythaLv (chlorochlamys aud 

 persa) and a number of Psittaci. So far as I can see, one has to go 

 back to the common type for both. Corythaix (fig. 20) has a 

 remarkably short and wide gut, in correspondence with its frugi- 



Fig. 20. 



Corythaix chlmroehlamys ; intestinal tract, x, short-circuiting vessel divided. 



vorous habits. The duodenal loop is wide and straight. The cir- 

 cular loop is short ; its anterior portion forms a normal coil, is slung 

 at the circumference of the circular mesentery, and is supplied by 

 radiating branches of the median mesenteric vein. No doubt the 

 vestige of the yolk-duct occurs upon this; but in my specimens, 

 which were all affected with tubercular nodules on the gut, I 

 failed to identify it. The distal portion of the circular coU, along 

 which the oseca run in the primitive type, is pulled out into a narrow 

 subsidiary loop, the distal portion of which gives a short-circuiting 

 vein to the duodenal vein. The rectum is straight, and there was 

 no trace of cseca. The gut appears to be directly derived from the 

 primitive type by shortening and by loss of the cseca, the distal 



