306 ZOOTOMY. 



211. The rounded aperture between the sacculus rotundus and the 

 colon, its margins forming the ileo-colic valve. 



212. The spiral valve of the caecum, a narrow spiral band projecting 

 into the cavity of the blind gut and corresponding with the external 

 marking. 



213. The intra-colic valve, a prominent fold occurring at the bend 

 between the two portions of the colon. 



214. The thick glandular walls of the appendix vermiformis and 

 sacculus rotundus : the very thin walls of the caecum itself, and the 

 minute papillary elevations with which its inner surface and that of the 

 spiral valve are beset. 



215. The absence of villi in the large intestine : the papillary surface 

 of the mucous membrane of the colon, the smooth character of that of 

 the rectum. 



XXIII. Tic the postcaval vein at the points where it 

 enters and leaves the liver : remove the whole of 

 the liver, with the exception of the part which 

 surrounds the postcaval. Note : 



216. The transparent, shining central tendon of the 

 diaphragm, and the muscular fibres which radiate from 

 it to the body walls, and are collected dorsally into 

 two strong bands of muscle, the pillars of the dia- 

 phragm, which pass backwards to their origin from the 

 anterior lumbar vertebrae. 



217. The aorta, passing from the abdominal cavity for- 

 wards between the pillars of the diaphragm. 



2 1 8. The oesophagus, passing through an aperture in the 

 dorsal region of the central tendon. 



219. The postcaval, passing through an aperture 

 situated to the right and ventral of that for the gullet. 



220. The three hepatic veins (Fig. 61, Ji.v), by which 

 the blood is taken from the liver to the postcaval : they are 

 best seen by slitting up the intra-hepatic part of that vein : 

 two of them enter the postcaval immediately posterior to 



