410 



MR. E. I. POCOClf ON THE KXTERXAL 



In Hi/drocha'i'iis the tip of the penis when contiacted is retro- 

 spective and close below tiie anus, in contaot vvitli the perineal 

 integument between the orifices of tlie pouches of thennal glands. 

 When distended the base of the penis is seen to arise just below 



A. Anal and genital region of Hjjdrochce^'us capybara, with penis retracted. 



B. The same showing the hase of the penis extended and the orifices of the anal 



pouches partially opened. 



C. The same with penis omitted and the anal pouches distended. 



D. Secreting area at the bottom of anal pouch. 



E. Transverse section through one of the pores of the glandular area. 



F. Lower view of glans penis. 



G. The same with glandular pouch cut open. 



a, anus ; ag, anal gland ; gu, genito-urinary orifice ; gp, glandular 

 pouch ; p, penis. 



those orifices in a position similar to that of the vulva (p. 418). 

 The penis is large, smooth, and cylindrical, with a narrowed apex, 

 beneath which lies the large genito-urinary orifice in the form of 

 a longitudinal slit when undilated. Behind this is the wide, 



