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Show 434 DR. E. C. STIRLING ON THE [Nov. 5, The literature bearing on these and other allied points has been concisely summarized by Messrs. Lister and Fletcher in the ' Proceedings' of this Society for 1881, p. 977. These authors also there record a condition of patency of the aforesaid opening in some species in which its existence had not been previously noted. I observe that while " no one as yet seems to have had the good fortune to find an embryo in any part of the vaginae," Messrs. Lister and Fletcher nevertheless come to the following conclusion, which I quote:-" In the very early condition of the Macropodidae the median canal is closed." Again they say:- " In some genera, viz. Macropus,Halmaturus, Petrogale (Dorcopsis and Dendrolagus ?), an opening is formed in the median canal to give passage to the young. This may take place in early life (Halmaturus), or not till young are about to be produced (Macropus). In the species Macropus major, however, this opening may or may not exist, and the young may be transmitted either through the median or the lateral canal." For one species of Kangaroo, at least, this question of the route taken by the embryo may be considered settled, for 1 have been fortunate enough to obtain a specimen of the female organs of Osphranter erubescens, Scl., which contain the embryo in course of transit along the passages. The organs in question, having been extracted by unskilled hands, were somewhat mutilated in the process, and further the operator, a cook in the camp of rabbiters, being a man of some intelligence and himself curious on the subject of marsupial parturition,had commenced an examination on his own account. These circumstances answer for the fact that the specimen is not anatomically complete, the lower part of the right lateral canal, a small part of the lower extremity of the left, and almost the whole of the urogenital passage having been cut away or left behind in the process of extraction. In tbe partial examination to which the specimen had been subjected before it came into m y hands, the median canal had also been partially slit up from the front; and in view of existing incisions I found it convenient to continue the dissection from this side instead of from the posterior (dorsal) aspect, by which the parts can be more satisfactorily displayed. Fortunately the essential parts and their relations to one another had not been disturbed, and the following is a brief description of the specimen, represented in the accompanying drawing (fig. 1, p. 435) of about four fifths of the natural size. The embryo, closely enveloped in a thin amnion, was 11, 6, and 5 m m . in the long, antero-posterior, and lateral diameters respectively ; its anterior extremities distinctly five-partite, and the posterior distinctly three-partite and smaller than the anterior. The eyes just discernible as dark rings. It was suspended by a cord, which was extremely attenuated for some little distance from its point of attachment, though on unravelling this it was found to be distinctly membranous even at its thinnest part. The exact method of attachment of the cord to the body of the embryo cannot be stated with exactitude in this specimen, owing to the laceration which |