154 MR, P, CHALMERS MITCHELL ON THE [Jan. 14, 
gutas 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 the 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 the ceca 
no longer run along it, but occur as very short stumps upon the 
rectum. 
CUCULIFORMES, 
Of these, I have examined only Corythaiw (chlorochlamys and 
persa) and a number of Psittaci. So faras I can see, one has to go © 
back to the common type for both. Corythaiw (fig. 20) has a 
remarkably short and wide gut, in correspondence with its frugi- 
Corythaix chlorochlamys ; 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 coil, along 
which the ceca 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 ceca. The gut appears to be directly derived from the 
primitive type by shortening and by loss of the cxca, the distal 
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