M ALE ORGANS OF RODENTS. 



653 



unprovided with the horny armature which gives it so remarkable 

 a character in the Cavies. 



In the Beaver {Castor canadensis) I have usually found the 

 testes, fig, 508, r, s, though small in proportion to the bulk of 

 the animal, lodged in subcutaneous depressions between the 

 castor-bags ; but with the usual wide opening of the « tunica 

 vaginalis,' permitting easy re- 

 turn of the gland into the 508 

 abdomen. The tortuous dis- 

 position of the vasa deferentia 

 would favour such periodical 

 movements of the testes: the 

 terminal portion of the ducts, 

 fig. 508, a, is dilated, or en- 

 larged by glandular thickening 

 of the walls, the inner surface 

 of which is multiplicate. The 

 vesicular glands are (for Ro- 

 dents) moderate sized convo- 

 luted bags, fig. 508, o, p : the 

 duct, fig. 509, d, sometimes 

 communicates with, sometimes 

 terminates distinctly from, the 

 contiguous vas deferens, ib. a. 

 The prostatic glands, ib. c, c, 

 are a cluster of shorter pyri- 

 form sacs, the long slender 

 ducts of which intercommuni- 

 cate before terminating in the urethra. The protometra, ib. b, b, 

 soon divides, after its communication with the urethra, into two 

 long c cornua,' which lie on the peritoneal fold behind the neck of 

 the bladder, mesiacl of the vasa deferentia, the course of which 

 they follow till they become too attenuated for distinction. The 

 Cowperian glands, fig. 508, m, n, are of a compact oval form, 

 situated between the ( erectores' and ( accelerators ' muscles ; and 

 opening into the bulb of the urethra. The maximised preputial 

 glands, ib. e, f, and ano-preputial glands, g, It, h, i, have already 

 been described. 



In the Water-vole (Arvicola amphibia) the epididymis, fig. 510, 

 /, g, is connected by longer ' vasa efferentia ' than usual with the 

 testes, ib. c, d. The vesicular glands, ib. k, /, relatively larger 

 than in Castor, are bent upon themselves, and subdivided along 

 one border : each prostate consists of three lobes, ib. m — r, or 



Male organs, Beaver, cxxi". 



