152 MR. P, CHALMERS MITCHELL ON THE (Jan. 14, 
and blood-vessels remains as in Numenius; but the large subsi- 
diary loop, on the distal limb of which lies the yolk-sac vestige, 18 
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 cxca 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 ceca are reduced. Larus martnus (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 Limicole, are more developed on the side 
Fig. 17. 
Larus marinus ; intestinal tract. , short-circuiting 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 Limicole 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 Charadriiformes generally, the anterior portion 
aS 
