THE URINO-GENITAL SYSTEM 287 



a series of deep knife-like ridges. These ridges are really composed 

 of a number of long fine papillae amalgamated together, at the apices 

 of which are the openings of the cloacal gland. The ridges are radi- 

 ally arranged with the anterior extremity of the cloaca at the approxi- 

 mate centre. Finally there is a slight median ridge passing along the 

 dorsal wall of the cloaca, which apparently corresponds with the 

 structure labelled /)«?;//j in Heidenhain's figures of Triton, but it is 

 very much less developed in Salamandra. 



Histologically the glandular mass is divisible into three portions, 

 called by Heidenhain the pelvic gland, the abdominal gland, and the 

 cloacal gland. Of these the cloacal gland forms by far the largest 

 portion and lies ventrally, i.e. ventral to the lateral diverticula above- 

 mentioned, the abdominal gland lies postero-dorsally, and the pelvic 

 gland antero-dorsally. The abdominal gland is very small and is not 

 easy to distinguish from the pelvic gland, thus contrasting strongly 

 with Triton, where the abdominal gland is well developed. 



On removing the skin the cloacal gland {^ = glandulae ani. Funk), 

 appears as a heart-shaped structure (gl.cl.') surrounding the cloacal 

 opening, and is seen to consist of a mass of coarse tubules. This ex- 

 panded ventral portion of the gland is separated from a corresponding 

 dorsal portion (gl.cl.") by the M. caudali-pubo-ischio-tibialis and M. 

 ischio-caudalis, the two parts being connected by a mesial portion 

 alongside the cloacal wall. It discharges its secretion by numerous 

 fine pores situated at the extremities of the long papillae arranged in 

 the cloacal walls as already described, as well as on the cloacal papilla. 

 The abdominal and -pelvic glands open on the dorsal cloacal wall. 

 Their tubules are smaller than those of the cloacal gland, and their 

 openings are either flush with the surface or on very low papillae. 

 The most anterior portion of the cloaca, i.e. the portion which ad- 

 joins the rectum, consists of a wide tube with folded walls, and its 

 epithelium is ciliated. In addition to the most anterior tubules of the 

 pelvic gland it receives the rectum, the urino-genital ducts, and the 

 bladder. The rectum merges directly into it, while the Wolffian ducts 

 enter it at the apices of a pair of small urino-genital papillae on its 

 dorsal wall (pap.u-g.), situated on either side of the middle line at the 

 anterior end. These openings are relatively farther forwards in the 

 male than in the female, and apparently correspond with the penis 

 divisus of Funk. The opening of the bladder is not, as might be 

 expected, at the extreme posterior end of this organ but a short dis- 

 tance anterior to it, and consists of a longitudinal slit in its dorsal 

 wall which opens ventrally into the cloaca immediately opposite the 

 urino-genital papillae (Fig. 71). Thus, although there is no direct 



