810 ON THE UROGENITAL ORGANS OF THE KANGAROO, 



There are also slight variations in the positions of the two 

 apertures with regard to the median ridge. Except in one case 

 these nine specimens call for no further comment. In the case 

 referred to, on slitting up the urogenital passage but one aperture 

 about | inch long, which is longer than usual, was to be seen. 

 On further examination this proved to be the aperture of a small 

 cavity into which the two canals open, and on the wall of which 

 the two orifices are easily made out. 



The two remaining specimens at the time of their being shot 

 were set aside as being probably in the virgin condition. In 

 both cases the pouches and teats were rudimentary, the ovaries 

 shew no corpora lutea, and the organs were so small that twenty 

 sections from the region of the embouchures of the lateral canals 

 are easily accommodated under a f- in. square cover-glass. 



In the first of them examined the sections beyond the difference 

 in size are very similar to the corresponding ones from No. (c.) 

 Osphranter robustus. In sections in which the urogenital canal first 

 appears, the prolongation of the cavity of the mesial cul-de-sac 

 appears as an arc of a circle with its concavity towards the urethra. 

 Its height from above downwards is about one half, and its width 

 from side to side about twice, the corresponding measurements 

 of the urethra. The following changes then take place. The 

 width of the aperture from side to side gradually decreases, but 

 on one side more than the other, until instead of projecting 

 beyond the urethra on both sides it now does so on one side only. 

 Next it appears split into four by transverse partitions, showing 

 that the bottom of the cavity is nearly reached. The same thing 

 happens in Osphranter robustus, No. (e.). Two of the holes then 

 disappear, the remaining two being very small and situated to 

 one side of the middle line. In the fifth section after this the cavity 

 comes to an ond, the last trace of it being situated just below 

 and close to one end of the elliptical urethra. Two sections 

 however before this happens there has become visible in the 

 middle line, about half way between the urothra and the uro- 



