INTESTINAL TEACT OF BIRDS. 



249 



supra-duodenal loop possibly is rather better separated from the general sweep of Meckel's 

 tract. In the others, except Gymnoglaux, a slightly more apocentric modification has 

 taken place. In Syrnium aluco, for instance (fig. 67), the duodenum is as in the others. 

 Loop " a " of Meckel's tract is as in Strix, but the region between this and the diver- 

 ticulum is much enlarged, so that the diverticulum is no longer at the apex of the circular 

 expansion. The supra-duodenal loop has increased very much in size, and is well separated 



Fig. 67. 



Intestinal Tract of Syrnium aluco. 



from Meckel's tract, and drained by a series of "bridging" veins, In Bubo maculosus 

 and B. poensisilie conditions are very similar to that in Syrnium. but the part of Meckel's 

 tract anterior to the diverticulum appears in two well-marked loops, a conformation 

 which recalls that in many of the Coraciae. In Gymnoglaux, possibly in association with 

 its small size, a simplification of the gut has taken place, with the result that there exists 

 conformation closely resembling that in many of the Rollers and other simple short- 

 gutted Coraciiform birds. Meckel's tract is thrown into two wide loops separated by 

 the diverticulum, the posterior loop being a wide supra-duodenal loop with bridging 

 veins. 



