CHARACTERS OF SOME IIYSTRICOMORPH ROBEXTS, 417 



ill spirit-preserved material. In a male of Coendu novce-hisjxinice, 

 however, in which the anus opens near the centre of a very 

 large naked area, without integumental ridges, and with the 

 penis at its lower extremity, there appeared to be a median 

 longitudinal mass of glandular tissue, without definite orifice, 

 showing through the skin of the longish perineal area between 

 the anus and the penis. Possibly this represents the coalesced and 

 partially aborted paired glands oi Hi/strix. (Text-figs. 20, G. H ; 

 26, G. F.) 



In 2Iyocastor the anus, with a few hairs i-ound the orifice, 

 forms a pi-ojection in the centre of a naked area a little distance 

 below the root of the tail. In the female this naked area is 

 continued round the genito-ui-inary region ; but in the male the 

 long perineal area is hairy. The anal glands in both sexes form 

 a solid median mass, opening by four pairs of small papillate 

 orifices into a sac which can be extruded by evagination just 

 beneath the anus. (Text-figs. 21, F-H ; 27, A, B.) 



In Capromys the anus is on an eminence a little way below 

 the base of the tail in the upper half of a naked area of skin 

 which extends downwards to the prepuce of the penis or clitoris. 

 When it is dilated the single orifice of the anal gland may be 

 seen immediately beneath it within the sphincter. This orifice 

 leads into a small pocket filled with the secretion of the gland 

 which lies mainly behind the pocket. The gland seems to resemble 

 in all respects that of Octodon, and differs from that of 2fyocastor 

 in being much smaller, apparently unprovided with papillae and 

 also incapable of evagination. (Text-figs. 21, A; 27, C, D.) 



In Octodon the anus also opens on a prominence a little way 

 below the base of the tail and about the same distance above the 

 prepuce in both sexes, the pei'ineal region and the area round 

 the prepuce being naked. The anal gland is a median mass with 

 a small sac opening just beneath the anus by a median orifice, 

 but concealed from view unless the latter is distended. (Text- 

 figs. 22, B, C; 27, E.) 



In Ctenom.ys the anus is more dilated than in Octodon, and its 

 walls inside are symmetrically wrinkled ; but in the single male 

 example examined I was unable to satisfy myself as to the 

 presence of a gland such as is seen in Octodon. According to 

 Tallberg, however, a gland similar in position and structure 

 to that of Octodon is found in C'tenomys, Echimys, Xelomys, 

 Cannabateomys, and Abrocoina. (Text-fig. 22, E, D.) 



In Lagostomus the anus lies just beneath a haiiy excrescence 

 some distance below the root of the tail. Just within the 

 sphincter may be seen the apertures of the anal glands opening 

 just below the orifice. From each side of the subcircular anus 

 a ridge of skin runs downwards, forwards, and obliquely inwards 

 to meet its fellow of the opposite side in a point, the two 

 forming the lateral margins of an acutely angled glandular area 

 covered with short hair. (Text-fig. 25, E. F.) 



In Chinchilla the anus also forms a marked projection some 



