150 MR. P. CHAIiMEnS MITCHELL OX THE [Jan. 14, 



down by the remnant of a primitive ventral mesentery. The last 

 minor loop of the circular portion of the gut has the long cteca 

 running forward alongside it. It is drained in the usual fashion 

 by a branch of the mid-raesenteric vein and by short circuit branches 

 from the duodenal vein. At first sight there ia a striking similarity 

 between the gut of the ]lails and thegut oFi'\{Zjnants(fig. 7, p. 143); 

 but this is due simply to the narrowness and regularity of the loofis. 

 The position of the yolk-duct vestige differs in the two, while the 

 short caeca and the kinks immediately above them make absolutely 

 distinctive characters in the Petrel. 



In the Dicholophidae and the Otididae the Ealline characters are 

 still obvious, but the gut is still shorter and the loops more definite. 

 Cariama cristata (fig. 14) shows the duodennm and the rectum 

 identical with the TJails ; the last portion of the circular loop is 



rig. 14. 



Cariama cristata ; inteatinal tract, .r, short-circuiting vessel divided. 



identical in its arrangement and veins, although the coeca are still 

 larger. The rest of the mid-gut is reduced, the third loop being 

 absent. The yolk-duct vestige is in the same place upon the 

 second loop, but the first loop of the circular mid-gut is partly 

 united with the second. In the Otidida3 the gut appears to be 

 further modified in the direction in which Cariama differs from 

 Gre.v. The duodenum, the rectum, and the last loop of the mid-gut 

 are as in the Rails and Gariama ; but the remainder of the mid-gut 

 is reduced to a single loop, corresponding to the second of that 

 region in Grex, and bearing the yolk-sac vestige on its distal limb. 



CnAEADniironMES. 



. The birds associated in this Order display a very varied series of 

 divergences from the type. Among those Limicoloe that I have 



