DR. w. w. Ely's notes on chapter ii. 303 



with the castoreum sacs, and are pyriform in shape. Each has a 

 duct, which opens within, by the side of the cloacal orifice at its 

 upper margin, surrounded by a dark areola. On everting the 

 oriiice of the duct, it appears to be a cul-de-sac, having three 

 minute orifices at its bottom Although each oil sac appears as 

 one, there is, in addition to the principal gland, two smaller ones, 

 which may be separated, each having its communication with the 

 tube which furnishes the outlet; in each cavity are hairs loose or 

 growing from its surface, and the smaller cavities are sometimes 

 filled with them. The walls of the oil sacs are much thicker than 

 the castoreum sacs, and contain many follicles of consideral)le size. 

 The cavities contain a thick, oily, creamy fluid. From the larger 

 cavity, about two drachms were obtained, having, when recent, 

 a faint odor of castoreum. This secretion, after standing six 

 months, is about half clear oil, and the remainder a whitish sedi- 

 ment. The whole is soluble in ether, except a small residue of 

 epithelial matter, but the oil is sparingly soluble in strong alcohol. 

 In a female beaver. Fig. 3, the castoreum sacs are 5^" long, and 8" 

 broad. The oil sacs are 2|" long. The amount of castoreum in 

 these sacs was small and dark colored. 



The Rodents, as a class, are very prolific ; this is true of the 

 beaver. Their genital organs are consequently strongly developed. 

 The statement of Cuvier, however, that the size of the testicles 

 in the Rodents exceeds ordinarily that of the kidneys, is not true 

 of this animal. Yiii. 104. 



In Fig. 1, the form of the penis is shown, curved and retracted. 

 When extended it is five inches long, and 1|" in circumference. 

 The glans is flattened, 1" 20''' in length, and covered with a 

 rough integument. It contains a bone equal to its length, and 

 largest at the base. The transverse communication of the casto- 

 reum sacs is behind the prepuce. The urethra has a spongy portion 

 3i" long, and a membranous one 2^". Cowper's glands lie be- 

 hind the pubis. The prostate glands lie by the side of the ure- 

 thra at its origin. The vesiculae seminales are united, and lie 

 behind the neck of the bladder, each being 1" 80'" long, 90"' 

 wide, and 60'" thick. It is possible that these glands were hy- 

 pertrophied, as their cavities contained a dense fibrous substance, 

 a portion of which had escaped into the urethra, distending and 

 obstructing its membranous portion. The testicles are contained 

 in a sac projecting from the inguinal opening, and are 1^" iu 

 length. 



