1896.] ANATOMY OF THE HOATZIIf. 619 



laboratory at the Gardens in the course o£ my investigations into 

 the anatomy of birds. A number of important memoirs have 

 appeared upon the Hoatzin, but, in the present condition of our 

 knowledge of the relations among the groups of birds, additional 

 details concerning the structure of a type so aberrant may prove 

 useful. 



Alimentary Ganal. 



The extraordinary crop and the general characters of the gizzard 

 and intestines bave been sufficiently described by L'Herminier ' 

 and Gadow °. Following the method which I have described in a 

 former paper ', I dissected out the coils of the intestine and the 



Fig. 1. 



Intestinal convolutions of Opisthocomus cristatus. 

 a, bridging- vessel divided ; t/.m., mesentery of the yolk-sac vestige. 



great veins in a well-grown chick and in three adults. As shown 

 in figure 1, the duodenal loop is unusually short and wide, and is 

 much less specialized than in most other birds I have examined. 



• " Reeherohes anatomiqucs ear quelquos genres d'oiseaux rares ou pou 

 connus," Ann. Sci. Nnl. s^r. 2, Zoologie, viii. I'aris, 1837. 



' " On the Taxonomio Value of the Intestinal Convolutions in Birds," 

 P. Z. S. 1889, p. 303. 



' " On the Intestinal Tracts of Birds," P. Z. S. 1896, p. 136. 



40* 



