ANATOMY OF THE DRILL. 



441 



The prostate (P.G) consists of a firm pyramidal part enclosed 

 in a capsTile, and a triangular part which is softer and lobulated 

 (T.P.P). 



The vesiculce semincdes (Y .H) {\.re two immense masses of lobules 

 bound together by connective tissue and ductules. Many nerves 

 run into them. Their ducts are long, and fuse with the vasa 

 deferentin . 



The corpo7'a cavernosa penis have large expanded bases. 



The Organs of Circulation. 



The Aeari (text-fig. 17 A) is 3"5 inches long, 2 5 inches wide, 

 and 2 inches thick. Its apex is less pointed than in some 

 Primates, and is composed entirely of the thin-walled right 

 ventricle. The thick-walled left ventricle falls short of the apex 

 by half an inch. The right auricular appendix is pointed, and 

 separated froin the aorta by a distinct interval. It is slightly 



Text-figure 17. 



The heart and aorta (A.), and spleen (B.). L.V. and R.V : left and 

 right ventricles. Other letters in text. 



notched as in some Marsupials. There are only a few small 

 columnfe carnetie. arranged along the inner sides of its walls. The 

 right auricle has few columna;. Between the orifice of the vena 

 cava inferior, which is not guarded by a valve, and the tricus23id 

 valve is a wide coronary opening. The right ventricle is capacious 

 and five papillary bundles give the chordse tendineae to th§ 



