INTESTINAL TRACT OF BIRDS. 



215 



completely lost the caeca. Paudion stands by itself; its i^ut is so extremely long that 

 none of the usual minor loops except the supra-caecal kink can be identified. Haliaiitus 

 is a simple modification of the Falconiform metacentre, tlie irregularity being due to 

 increase in length. For the Anseridae it is necessary to go back to the Pelargo-Colymbo- 

 morphine metacentre. Aiiseranas is practically in that position unmodified, save that 

 the ca;ca are still longer, a condition common to all the Anscrid.Te except some of the 

 Mergansers. The Cygnus type, with its three definite and contorted minor loops on 

 the anterior portion of Meckel's tract and its A'ery long axial loop with peculiar blood- 

 vessels, gives an Anserine metacentre from which Nettoptis and Spatula have diverged 

 still further. Mergus is probably a pseudocentric modification of the Spatula type. 



TINAMIFORMES. 



Crypturid^. — Of these I have been able to examine the intestinal tract of seA^ei*al 

 specimens of JUtyiichotus rnfescens and Nothiira maculosa. The conformation is prac- 

 tically identical in these two forms. The duodenum is a long narrow loop ; Meckel's 

 tract {Rhyuchotus rnfescens, fig. 36) is divided into two nearly equal parts, the large 



Fig. 30. 



Intestinal Tract of liliynclwtus rufescens. 

 c, compare loop similarly marked in Gruiforraes, figs. 41, 42, 43, &c. Other lettering as before. 



Meckel's diverticulum lying between the two. The first portion is one very long narrow 

 loop ; the second portion is an equally long and narrow supra-duodenal loop drained by a 

 branch of the middle mesenteric vein as well as by the usual " bridging " factor from tlic 

 duodenal vein. Meckel's diverticulum was very large in two specimens of Mhynchotus, 

 small in a third, and very small in Nothura. The small minor looj) just distad of it 



33* 



