INTESTINAL TRACT OF MAMMALS. 



231 



examined, the duodeniim consisted of two short loops marked off 

 by their larger calibre. The proximal limb of the pendant loop 

 and the beginning of the recurrent loop were thrown into long 

 and very irregnlar minor loops, distad of which the recurrent 

 limb had a straight course up to the middle dorsal line, where 

 it bent round sharply to pass into the sti'aight rectum. 



In 1905 I had not seen an example of a Bat with a caecum, and 

 was content merely to point out the general similarity between 

 the simple gut of Bats and of such Insectivores as f'entetes, with 

 the caution, however, that in neither case could it be asserted 

 safelv that the simplicity was piimitive. I am now able to add 



Text-fiffure 25. 



Intestinal tract of Artibens planirosfrls. 

 S. Cut end of intestine nearest stomach. E. Cut end of intestine nearest stomach. 



to the comparison. In Insectivores and Ciiiroptera the gut is 

 relatively short, disposed on a continuous primitive mesentery, 

 and in the extremer types shows little difterentiation. In the 

 Insectivores, however, tlie simplicity has been reached from a 

 condition in uhich the cpecum was developed a considerable 

 distance from the distal end of the pendant loop, and the upper 

 portion of the recurrent limb possessed n, large colic loop. In 

 the Chii-optera, the whole of the pendant loop gives rise to 

 Meckel's tract, the csecum being placed distnd of the passage of 

 tlie pendant loop into the straiglit rectum. 8o far, therefore, as 

 evidence is afforded by the gut-pattern, there is no reason to 

 associate Chiroptera with Insectivores. 



