236 THE SALAMANDER 



also receives the considerable addition of the following two median 



veins in the pelvic region. 



(a) The median cloacal vein (v.cl.m.) arises from the anterior and 

 mesial regions of the cloaca by several fine factors and runs forwards 

 in the middle line ventrally, along the pubo-ischiadic symphysis, 

 immediately under the skin. At the ypsiloid cartilage it bends round, 

 either to the right or left, and joins the abdominal vein in the middle 

 line at its formation by the fusion of the right and left pelvic veins. 



(J)) T\\t posterior vesica/ vein (Fig. 63 ; v.ves.p.) enters the abdominal 

 at the same point, but lies dorsa/ to the pubo-ischiadic symphysis. It 

 drains the blood from a rich vascular network spread over the pos- 

 terior region of the bladder, and receives a pair of veins from the 

 dorsal side of the pubo-ischium. These small factors are readily 

 broken when the pubo-ischiadic symphysis is split and pulled apart, 

 so that they are easily overlooked. They receive a small tributary 

 which passes through the obturator foramen from the ventral side. 



The abdominal vein passes forwards in the middle line from the 

 anterior edge of the pubes to the anterior extremity of the bladder 

 (about 14 mm.) through the subperitoneal epithelium, without re- 

 ceiving any further factor of importance other than a small ypsiloid 

 vein at the anterior end of the ypsiloid cartilage from the surrounding 

 tissues and skin of that region. 



At the anterior end of the bladder it is joined by vessels from this 

 organ. 



(c) One or more anterior vesical veins (Fig. (>y^ v.ves.a.) collecting 

 the blood from the anterior, ventral, and lateral regions of the bladder. 



(^) The vesico-haemorrhoidal vein (v.ves.hm.) comprising two main 

 factors. 



(i) A dorsal vesical vein formed by many factors from the dorsal 

 bladder-wall. These usually unite to form a single vessel before join- 

 ing the other factor, but may enter at several points. 



(ii) A ventral rectal vein. It is important to notice that the whole of 

 this vessel lies ventral to the gut, i.e. between it and the bladder. 

 The blood from the dorsal side of the rectum enters the portal vein 

 by means of the haemorrhoidal vein, but there appear to be frequent 

 fusions within the tissue of the rectum between the factors of these 

 two vessels. 



The combined dorsal vesical and ventral rectal veins form the 

 vesico-haemorrhoidal vein which enters the abdominal a little an- 

 terior to the bladder. 



In one case the abdominal vein divided at this point to reunite a 

 little farther on, forming a closed loop. Normally, however, it con- 



