320 Mil. R. H. BURNE ON THE [Apr. 18, 



although to a certain extent trabecular in structure, consists 

 practically of solid muscle. The ventricular septum is quite 

 normal. 



The great vessels arise from the ventricle in the usual positions, 

 but it is worth noting that the carotids, 7 cm. above their origin 

 from the innominate artery, suddenly dilate to at least twice 

 their original diameter and then very gradually narrow again 

 towards the head. 



The arches of the two aort?e are equal in size — 2 cm. in diameter 

 when ilattened. They unite on a level with tlie apex of the 

 ventricle. The cceliac artery arises from the left arch close to its 

 union with the right, the mesenteric from the left side of the 

 upper extremity of the abdominal aorta. 



The Veins. 



The Renal Portal System (text-fig. 72). — The chief affluent 

 (text-fig. 72, il.v.) of the afferent renal vein is formed by the 

 union of a number of small vessels upon the inner side of the 

 ilium. The trunk thus formed runs forward to the hinder end 

 of the kidney, and there divides into two branches — a dorsal one 

 (the afferent renal vein) that runs upon the medio-ventral sur- 

 face of the kidney, lateral to the ureter, and very soon becomes 

 embedded in the kidney-substance ; and a ventral branch that, 

 after taking up the obturator vein,, forms one of the roots of the 

 anterior abdominal vein. The latter branch lies upon tlie dorsal 

 surface of the intra-pelvic muscles, and appears upon the surface 

 of the body- wall in the pubo-epipubic notch. Just in front of 

 the epipubis it unites with its fellow of the opposite side, and the 

 trunk formed by the union runs forward in the substance of the 

 body-wall to the cleft between the ends of the coracoids. Here 

 it receives vessels from the muscles of the left coracoid, then dips 

 down towards the liver and enters it about the middle of the 

 ventral surface of the left lobe. This is the left anterior abdo- 

 minal vein. The right anterior abdominal vein is represented 

 only by the small vessel formed by the union of the veins 

 from the muscles of the light coracoid. It enters the posterior 

 edge of the isthmus of the liver about its middle, in relatively the 

 same position as the fully developed right anterior abdominal vein 

 of Emys. 



The persistence of only one (the left) anterior abdominal vein, 

 although normal in Amj^hibia and Lizards, is not the condition 

 generally described as typical of Chelonia, in which [Testudo, Emys) 

 both veins persist, forming right and left antei-ior abdominals. 

 I notice, however, that Rathke* mentions that in young indi- 

 viduals of Chelone and in his specimen of Dermochelys the left 

 anterior abdominal vein only is present. In Testudo grceca also 



* Ratlilve : Eiitwickl. p. 213. 



