iSQS.j ' : ISTESXItTAli TRACT OF BIBDS^ l4l 



described frequently, were marked by the attachment of a spiral 

 valve. But the rectal part of the intestine, that supplied by the 



^ Strtithio camelus ; intestinal tract. *, ehort-circuitiug vessel cut across. 



posterior mesenteric vein, is expanded into an enormous coil 

 swung at the circumference of a semicircular expansion of its 

 mesentery. Only in Chaiina and in the Eagles and Petrels have 

 i found the slightest trace of a convergent resemblance to this 

 feature, but in the latiter the subsidiary rectal loops, although sup- 

 plied by the rectal vessel, lie above the caeca. 



I have not yet had an opportunity of dissecting a Ehea or an 

 Apteryx i. 



It is plain that, so far as degree of divergence of type in the 

 alimentary canal goes, the Ratites deserve their accepted place at 

 the bottom of the avian scale. 



Carinat^. 

 coltmbifoemes. 



In these (Podiceps not examined") (fig. 5, p. 142) the duodenal loop 

 is straight and normal. The circular loop is pulled out into a series 

 of minor loops that are arranged almost symmetrically round the 

 middle mesenteric vein. ^ The yolk-sac vestige lies in front of the 

 middle point of the series. The last loop of the circular sj'stem 



• [In a E!Ka americana which I have more recently examined the gut was 

 intermediate in form between those of Casuarim and Siruthio, The anterior 

 portion resembled Casuarias ; the rectum had an expansion recalling that in the 

 Ostrich, but much less strongly marked. — P. 0. M., March ISGe.] 



