152 MB. p. CHALMBnS MITOHEH ON THE [Jan. 14, 



and blood-vessejs remains as in Numenius ; but the large subsi- 

 diary loop, on the distal limb of which lies the yolk-sac vestige, ia 

 pulled out into an enormously long narrow loop, which is then 

 rolled up into a spiral. The distal part of the circular loop is very 

 much reduced, although there still remains a small loop in the 

 position occupied by the long ca)ca of Numenius and giving a 

 vessel to the duodenal vein. 



The Gulls display a type that is more divergent than Nume- 

 nius, in that the csBca are reduced. Laras marinus (fig. 17) shows 

 that in other respects they are as primitive as Numenius. The 

 duodenum is a simple loop with the usual vessel. The circular 

 coil of the mid-gut is thrown into a series of irregular loops, which, 

 however, as in the Limicolie, are more developed on the side 



Eig. 17. 



Lams marinus ; intestinal tract, x, ehort-cirouiting vessel divided. 



anterior to the yolk-sac vestige. This lies in the normal position 

 opposite the end of the median mesenteric vein. The last part of 

 the circular loop forms an extended subsidiary loop supplied by a 

 short-circuiting vein from the duodenal vessel. I have not found 

 instances myself, but Dr. Gadow states that in some Gulls spiral 

 folds occur in the region corresponding to the spiral fold of Scolo- 

 pax. Thus the Gulls and the Limicolte would form a series of 

 divergences from the common type, but in parallel directions. 



Pterocles (fig. 18) diverges in yet another direction. The ex- 

 tremely primitive character of the gut is obvious at once. The 

 duodenum, the circular loop, and the rectum are all distinct and 

 have the usual veins. The middle of the mid-gut is marked by 

 the vestige of the yolk-sac placed at the end of the median mesen- 

 teric vein. As in Charadriif ormes generally, the anterior portion 



