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Show 986 MESSRS. LISTER AND FLETCHER ON THE [Dec. 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 subsiding 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 Lucii observed in Halmaturus billardieri. The orifices of the lateral canals are outside these 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 septum 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 M. rufus. In other respects the arrangement is similar. The median canal, instead of ending blindly as in the 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 urogenital chamber! The muscular constrictions toward the posterior part of the lateral canals are well marked, so that a small probe was admitted with difficulty ; a small fold of mucous membrane projects from the outer wall |