INTESTINAL TEACT OF BIRDS. 211 



invariably bears at its apex an unusually large Meckel's diverticulum. In many Falcons 

 the first portion of Meckel's tract displays the three minor loops which recur among 

 Pal coniform birds. In Falco melanogenys (fig. 32) and F. Feldeggi (fig. 33) two of these 

 have disappeared, probably in connection with the very great elongation of the tract as 

 a whole. The apical portion of Meckel's tract may be irregularly twisted as in the 



Fig. 33. 



Intestinal Tract of Falco Feldeggi. Lettering as before. 



Peregrine Falcon and in Falco melanogenys (fig. 32), or it may be coiled into an 

 irregular spiral, an apocentric peculiarity found in many specialized types, for instance 

 in Pigeons and Passerines. There is always a supra-duodenal loop and a supra-caBcal 

 kink. The caeca are vestigial ; in a Peregrine Falcon I found only one present. The 

 rectum is short and straight. 



3. In the Osprey, Pandion haliaetus (fig. 31), the gut is enormously long, 

 and is of very narrow calibre, a modification obviously in association with piscivorous 

 habit. The duodenum is long and narrow. Meckel's tract is thrown into a very large 

 number of narrow loops, arranged round a nearly circular mesenteric expanse, the 

 diverticulum being in the usual place at the central point of the curved system. There 

 is no supra-duodenal loop, but there is a small supra-csecal kink. The caeca are vestigial 

 and the rectum is short and straight. 



The Falconiformes are on the average rather large birds with diet in the main 

 carnivorous, with some exceptions which are piscivorous, and a few which live on 

 insects. Except in the piscivorous cases, there is little correction to be made for diet. 



