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Show 436 DR. E. c. STTRLTNG O N T H E [Nov. 5, had taken place before the specimen came to hand, to which laceration, in fact, the above-mentioned attenuation of the cord was due ; but there were distinct traces of a torn membrane similar to that constituting the cord attached to the edge of the umbilical aperture. A small coil of intestine protruded at the umbilicus, and no trace of allantois was visible external to the body. Following the course of the cord to its attachment, it is seen to pass through a well-defined orifice of about 2-3 mm. in diameter, which opened into the median canal. The edges of this opening were longitudinally corrugated. In this median canal the cord became thicker, and was visibly composed of a semitranslucent tubular membrane much crumpled longitudinally ; in its walls ran three considerable vessels. Indications of similar vessels could be traced back into the shrivelled and attenuated portion of the cord next to the embryo ; but, owing to the small size of the part of the vascular system of the embryo they communicated with, they could be hardly distinguished. This tubular cord continued though the median canal, which showed on the internal surface of its posterior (dorsal) wall a well-marked median raphe, rising in its lower part into a ridge of such prominence as to mark off two distinct channels ; and proceeding from this median ridge were conspicuous transverse and oblique striae, giving the surface a partly striated, partly reticulated appearance. The cord lay in the right hand of these divisions. The os of each uterus opened into the median canal through a prominent nipple-like projection only slightly larger than that on the left side, though the body of the organ on the right side was several times larger than its fellow. Traced through the os into the cavity of the right uterus the cord expanded into a thick and much plicated membrane, the folds of which dipped deeply down into corresponding sulci of the uterine lining. The two structures, however, were easily separable, there being apparently no vascular or other organic connection between them. Not being able to satisfy myself as to the exact nature of the connection between the cord and the embryo in the above specimen, on account of its small size and partly torn condition, I referred to a larger specimen of an embryo, probably of Macropus major, which I happened to possess. From the absence of a record concerning it, I am unable to be positively sure either of the species to which it belonged or of the conditions under which it was found, but for various reasons I have little doubt but that it was a uterine embryo belonging to the aforesaid species. This was 25 m m . long, exclusive of tail, and closely enveloped in a transparent amnion which was reflected from the cord to about an inch which still remained attached. The substance of the cord itself was formed of a close, tough membrane closely adherent to the edge of the umbilical aperture, and it concealed a small protruding loop of intestine. In its walls ran three vessels, the connections of which with the fcetal vascular system I need not repeat here, as I found them to be exactly as described oy Sir Richard Owen in his ' Anatomy of Vertebrates,' vol. iii. p. 719. |