BY T. TriO^rSON FLYNN, B.S(\ 149 



discussion, being first a rliomboidal mass situated between 

 the two inpassing ureters. Later, in company with the 

 two vaginae, it comes to lie jvist outside tne circularis of 

 the urethra as a deeply stained triangular mass. The cir- 

 cularis of the urethra develops an upper portion, which 

 grows over the two vaginae, and encloses them together 

 with the deeply staining tissue. The muscular layer here, 

 tlien, is in section of a somewhat elliptic shape, crossed by 

 another muscular layer, tne dorsal portion of the original 

 circularis of the urethra. In this way two spaces are form- 

 ed, an upper and smaller containing the vaginae with the 

 intervening deeply staining tissue, and a lower large one 

 containing the urethra. The muscular layer between these 

 two spaces disappears, and so is formed the circularis of the 

 ui'ogenital strand. The vaginae have up to this time each 

 kept its own circular mviscle layer. The muscle 1-ayer of 

 the vaginae consists each of an outer and inner circular 

 layer portion, with an intervening mass consisting of con- 

 necting tissue with a few circular fibres. Just before the 

 vaginae enter the urogenital sinus their muscular layer 

 dwindles away. The two vaginae enter the two dorsal 

 grooves of the ui'ogenital sinus, the presence of which gives 

 the sinus somewhat the shape in section of a V, the limbs 

 of the letter being formed by the grooves just mentioned. 

 The cloaca is covered with a stratified epithelium. 



REMAINS OF THE WOLFFIAN DUCT. 



In sectioning there was found in the course of the left 

 vagina round the bladder, embedded in its wall, between 

 the inner and outer portions of the circularis, a short, 

 blind discontinuous tube, representing, I take it, the re- 

 mains of the Wolffian Duct (Fig. 3). It extends through a 

 total length of 450 micra, thirty sections of 15 micra each. 

 Here and there it shows a lunven, at other places it is a 

 solid cell strand. It is thickest in the middle, and tapers 

 off at each end, leaving no trace. It is not found in the 

 similar position in the right vagina., nor in the multiparous 

 sjjecimen, nor have I found it in the pouch young. It is to be 

 regarded as an individual variation. Although remnants 

 of the Wolffian duct have beien found persistent in the 

 papilla uteri, it has never, so far as I know, been found in 

 the position above described. 



THE CLITORIS. 



Extremely little has been done on the clitoris of Mar- 

 supials. Those who early described the genital organs in 



