986 MESSRS. LISTER AND FLETCHER ON THE [DcC. 13, 



side the ventral wall of the urogenital chamber is raised into two 

 large distinct folds nearly 5 in. high, which run from the anterior 

 end parallel with the long axis for some 1| in., gradually sub- 

 siding as they proceed back. When the urogenital chamber was 

 opened from the dorsal side, these folds were seen meeting one another 

 in the middle line and quite shutting off from view the two orifices 

 situated between them. This is just what Luca observed in Halma- 

 turus billardieri. The orifices of the lateral canals are outside 

 tliese folds at the anterior end of the urogenital chamber. The folds 

 thus divide off a ventral median from a dorsal compartment. The 

 latter is most spacious at the sides where it is continuous with the 

 lateral canals. The walls of the urogenital chamber are covered with 

 fine papillae. 



With regard to the condition of the lateral vaginal canals, the 

 lining membrane was of the usual yellowish- white colour ; there was 

 no appearance whatever either of special vascularity, or of their 

 having been recently dilated by the passage of so large a body as the 

 foetal young. A small delicate ridge on the ventral median wall of 

 the anterior end of the median chamber, and a low rounded one at 

 its posterior end, are the only evidences of its origin from two 

 canals. 



The condition of the urogenital organs of the specimen b will be 

 described later. (See Note.) 



With regard to c, we have not been able to obtain any direct 

 evidence whether it had given birth to young or not. The urogenital 

 organs presented a similar structure to those of a ; but the walls of 

 the median canal were much less vascular. The median canal 

 opened by a well-marked orifice into the urogenital chamber. 



The specimen d was bred in the Gardens, and was known not to 

 have produced young. 



The median vaginal chamber is well developed and somewhat 

 dilated below. Its walls appear quite continuous with those of 

 the urogenital chamber. The dorsal wall of the median vaginal 

 chamber was opened ; and the canal was found to end blindly 

 posteriorly immediately dorsal to the orifice of the urethra ; a thin 

 semitransparent septu;n divided its cavity from that of the urogenital 

 chamber. The two longitudinal folds in the latter are as well marked 

 as in specimen a. 



The first specimen (a) of Macropus major which has come into 

 our possession had produced young in the Society's Gardens. 



In this species the lateral canals describe a wider arch and the 

 median canal became more narrow posteriorly than in J/. i-ufus. 

 In other respects the arrangement is similar. The median canal, 

 instead of ending blindly as in tbe specimens hitherto described, 

 communicates by a distinct and wide aperture with the urogenital 

 sinus, in the same position as in M. rufus a and c. There are, 

 however, no distinct longitudinal folds in the vu'ogenital chamber. 

 The muscular constrictions toward the posterior part of the lateral 

 canals are well marked, so that a small probe was admitted with difl"!- 

 culty ; a small fold of mucous membrane projects from the outer wall 



