| OCR Text |
Show 1896.] INTESTINAL TRACT OF BIRDS. 151 examined, Numenius (fig. 15) certainly is nearest the common type. The duodenum is a simple loop supplied with the usual vein ; the circular loop is nearly symmetrical, and the vestige of the yolk-duct Fig. 15. Numenius arquata ; intestinal tract, x, short-circuiting vessel divided. occurs about the middle of its length. As in the Rails this is remarkably large even in adult life, and frequently is bent on itself and tied down by remains of the primitive ventral mesentery. The long caeca lie alongside the posterior part of the circular coil, which gives a short-circuiting vein to the duodenal vessel. The rectum is straight. Glareola resembles Numenius, but is even simpler. In other Limicola? the general tendency is to an asymmetrical extension of the circular loop and to a reduction of the caeca. The Woodcock (fig. 16) may be taken as an extreme case of this kind of divergence. The general arrangement of the loops Fig. 16. Scolopax rusticola ; intestinal tract, x, short-circuiting vessel divided. |
