INTESTINAL TRACT OF BIEDS. 



231 



base, and the supra-duodenal loop is better separated. In Recur cirostra avncetta a still 

 more apocentric modification in the same direction is reached. The axial loop has 

 grown outwards to more than twice the length attained in Tringa, and is folded irregu- 

 larly as a flat ribbon, partly rolled on itself and partly spirally twisted. The caeca 

 remain long, and the other parts of the gut are as in Tringa. A still greater apocentric 

 divergence of precisely the same kind occurs in Scolopax rusticola (Plate 22). I have 

 already figured the very remarkable conformation assumed by its gut (26. fig. 16). The 



Fig. 50. 



Intestinal Tract of Chionis alba. Lettering as in fig. 41. 



change is simply that the axial loop has grown still longer than in JLecurvirostra, and 

 the rolling-up and spiral twist is still better marked. The caeca have degenerated, and 

 have left isolated a small supra- duodenal loop with a bridging vein. 



CHIONID^:. Chionis alba (fig. 50) shows a comparatively slight modification of the 

 Numenius type, and is plainly much more archecentric than most of the Charadriidae. 

 Mecke!' s tract is relatively longer ; the axial fold with its large Meckel's diverticulum is 



35* 



