| OCR Text |
Show 1896.] INTESTINAL TRACT OF BIRDS. 153 of the circular loop is expanded. In Pterocles it forms a long narrow loop, the end of which is bent upon itself. The posterior Fig. 18. Pterocles bicinctus ; intestinal tract, x, short-circuiting vessel divided. part of the circular loop remains in the primitive condition, and has the long caeca attached to it. A short-circuiting vein from the duodenum is present. The rectum is straight. In the Columbae which I have examined (Columbce of several species, Phlogoenas cruenta) (fig. 19), it is tempting to regard the Fig. 19. Columba livia; intestinal tract; the spiral is figured as rather too symmetrical. x, short-circuiting vessel divided. |
