PHTLOGENY OP THE PAL2EOGNATIOE AJSTD NEOGNATHJE. 249 



degree of divergence of type in the alimentary canal goes, the Ratites deserve their 

 accepted place at the bottom of the avian scale." 



I have been enabled to examine the intestines of all the Palceognathce, save 

 Struthio. So far as my material goes it entirely confirms the observations of Gadow, 

 Mitchell, and Beddard. 



Casuarius, Dromcms, and Apteryx all resemble one another rather closely. 



In Casuarius and Dromceus the duodenal loop is wide, in Apieryx narrow. In 

 Casuarius, as Mr. Mitchell points out, the pancreatic and hepatic ducts open into a 

 diverticulum of the distal loop. In Dromceus and Apteryx the duodenum is longer and 

 narrower, and the pancreatic and hepatic ducts open separately into the duodenum. 

 In other genera the small intestine is relatively short, and the convolutions therefore 

 are simple. The rectum is short and straight ; in Casuarius and Dromwus its inner 

 lining is thrown into a number of strongly marked irregular rugous folds. 



In Casuarius and Dromceus the caeca are relatively short, of a uniform thickness 

 throughout, and have a narrow lumen. In Apteryx the caeca are relatively much 

 longer, exceeding 6 inches in length, whereas in the two former they do not exceed 

 5 inches. Furthermore, in Apteryx the terminal half becomes suddenly and markedly 

 dilated ; each caecum thus presents a sausage-shaped free end, borne on a narrow tube- 

 like stem. 



There are no valvular appendages in the caeca of these three forms. 



Rhea is intermediate between Casuarius on the one hand and Struthio on the other. 

 The duodenal loop is narrow and closed. The convolutions of the small intestine 

 resemble Casuarius, the posterior rectal portion Struthio. The pancreatic and hepatic 

 ducts open separately. The resemblance to Struthio consists in the relatively great 

 length of the rectum ; but it differs therefrom in that it is only thrown into a single, 

 and not a series of complex loops. 



The ceeca are relatively of enormous length, exceeding those of any other Palceo- 

 gnathe. They appear, however, to vary in this respect very considerably. In the 

 series of measurements given by Kemouchamps [85] the variations in R. macro- 

 rhyncha range between 1 foot 4-J inches and 2 feet 9 inches ; in R. americana between 

 2 feet 4 inches and 4 feet 8 inches. In a female of this latter species dissected by me 

 they attained a length of 5 feet 3 inches, accompanying the small intestine throughout 

 the greater part of its length. The lumen was sacculated to within a short distance 

 of the extreme end of the caecum by means of a series of semilunar valves alternating 

 one with another. The position of these valves was indicated on the outside of the 

 caecum by means of a series of constrictions (fig. 7, p. 250). 



The intestinal coils of Struthio I have not had the good fortune to examine. I 

 therefore append Mr. Mitchell's description [60]. lie writes: — "The first two parts 

 of the intestine and the three great veins were according to type, the yolk-sac 

 diverticulum being conspicuous in the circular loop opposite the end of the median 



