636 ANATOMY OF VERTEBRATES. 



is seen to be a large pyriform bag, fig. 497, p, with a corru- 

 gated glandular lining membrane, r; the pair terminates by a 

 common orifice, q, in the ano-preputial passage, q, e, a: the 

 other mass may be separated into three rather compact glands, 

 o, I, h, with short ducts, ending by a common orifice, e, e, on 

 the same passage, nearer the anus, a. The secretion of these 

 latter glands is yellow, viscid, and musky; that of the upper 

 bags, p, r, is greyish-coloured and more offensive: both secretions 

 appear to be mixed in the dried ' castoreum ' of commerce, of 

 which that from the Castor fiber of Europe and Asia has a higher 

 value than the ' New England castor,' obtained from the American 

 beaver. 



Homologues of the glands, o, h, of smaller size and simpler 

 structure exist in many Rodents, and are reckoned as ( anal : ' 

 they are shown in the Agouti, at r, s, fig. 506 ; in the water-vole, 

 at t, fig. 510; in the male hare, at k, 7, fig. 505; and in the female 

 hare at q, fig. 539. In Lepus the follicles open into a deep glan- 

 dular fossa occupying the interspace between the rectum and 

 prepuce, on each side. Hunter, after noting in a male Helamys 

 capensis the position of the vent ( about two inches from the tail,' 

 proceeds to state: — ' About half-an-inch farther between the legs 

 is another opening, similar to the anus, passing in the same direc- 

 tion between the two crura of the os pubis, and leading to, or ter- 

 minating in, two blind ends, between the rectum and the bulbous 

 part of the urethra. These two ends are glandular, or secrete a 

 whitish mucus ; they are lined with a cuticle, are white and silky, 

 having a good deal of short white hair.' l On each side of the ter- 

 mination of the rectum in the cloaca of the Ornithorhynchus there 

 is an oblong glandular prominence, about four lines in length and 

 two in breadth, on which there are about ten orifices of follicles 

 which secrete a scented sebaceous matter. In all Marsupials two 

 similar cavities with sebaceous follicles open into, or near to the 

 termination of the rectum. The short vestibular or cloacal pas- 

 sage in the two-toed Sloth shows many orifices of such follicles. 

 A pair of small anal bags exude their secretion near the verge of 

 the anus in the Armadillos. 



The anal gland-bags are most constant and best developed, as 

 a rule, in the Carnivorous order : they are each provided with a 

 muscular capsule, fig. 498, «, and present a smooth surface when 

 this is removed, as at b : they are, also, commonly smooth within, 

 and lined by a dense epithelium : the glandular stratum is some- 



1 ccxxxvi. vol. ii. p. 239. 



