562 



MR. F, E. BEDDAEB ON THE ANATOMY OF [May 26, 



characters of that organ in discriminating between these allied 

 genera. 



Text-fi2-. 111. 



Alimentary tract of Antecliinomys laniger. 

 O. Omentum. O'. Splenic omentum. St. Stomach. 



The intestine presents a number of features of intei-est. It is 

 in the first place very short, as Mr. Alston has pointed out. 

 Furthermore, there is no external difierentiation into sections. 

 The tube has the same bore throughout, and the absence of any 

 trace of a caecum renders it impossible to fix the delimitation 

 between ileum and colon. The alimentary tract is not only 

 short but, comparatively speaking, rather wide. There is no 

 duodenal loop to be distinguished from the rest of the tube. 

 The interesting fact about the intestine is that the whole tube 

 is suspended from the middle line of the dorsal parietes by a 

 single continuous mesentery. This is absolutely uncomplicated 

 by any secondary attachments of any sections of the gut to each 

 other, or to the parietes. In other mammals there is at least (in 

 the majority of cases at any rate) one folding of the gut upon 

 itself. That is, in the region of the stomach the transverse colon 

 lies above the duodenum just after it issues from the stomach, 

 and there is in this region a more or less direct mesenteric 

 secondary connection between the duodenum and the colon or 

 mesocolon. There is nothing of the kind in Antechinomys. 



Another point of importance to be noted in relation to the 

 intestine is that the loops into which it is thrown are not fixed. 

 The whole intestine can be straightened, or rather of course 

 thrown into a continuous curve, and thus differs markedly from 

 many forms where the foldings of the intestine are permanent 

 foldings and cannot be straightened out without tearing the 

 supporting mesentery. Indeed, it is not too much to say that 

 the alimentary tract of this mammal is as simple as that of 

 any Lizard. 



