1896.] IITTBSTINAL TBA.CT OP BIEDS. 155 



loop of the mid-gut with its special vein apparently being a remi- 

 niscence of the stage with functional caeca. 



In the Parrots, Macaws, and Parrakeets that I have examined 

 the gut presents no great divergences. It is invariably very long 

 and slender, and the subsidiary loops are folded upon each other, 

 and twisted and doubled in a very perplexing manner. Moreover, 

 the masses of twisted gut are overgrown by connective tissue loaded 

 with fat, and short-circuiting connections between the veins are 

 common. The relation to the common type, however, is easily 

 made out. Ara ararauna (fig. 21) may serve as an instance ; the 



Pig. 21. 



Ara ararauna ; intestinal tract, x, short-circuiting vessel divided. 



duodenum is considerably wider than the rest of the gut, and is a 

 simple loop, partly curved at the end. The circular loop is enor- 

 mously expanded and is pulled out into a number of subsidiary 

 loops, four in number, as in Ara, but numerous minor subsidiary 

 loops usually occur between them. The first of the four is short 

 in Ara ; the second, as in the others that I have examined, bears 

 the vestige of the yolk-duct at its extremity ; the third and fourth 

 are very long, and the fourth has a short-circuiting vein to the duo- 

 denum, and corresponds to the part of the circular loop along which 

 the coBca run in the primitive type. The rectum is straight and 

 bears no trace of cseca. The three main veins — the duodenal, the 

 median, and the posterior mesenteric — occur in the typical fashion. 

 When the minor loops between the four subsidiary loops are 

 abundant, as, for instance, in Chryosotis, the gut bears a resemblance 



