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Kangaroo." By Richard Owen, Esq., Member and Assistant Conser- 

 vator of the Museum of the Royal College of Surgeons, London. 

 Communicated by Sir Anthony Carlisle, F.R.S. — was commenced. 



May 1, 1834. 



BENJAMIN COLLINS BRODlE,Esq.,Vice-President,inthe Chair. 



Mr. Owen's paper was resumed, and concluded. 



The author gives a history of the opinions which have been ad- 

 vanced relative to the generative organs and functions of the Marsu- 

 piata, an extensive order of quadrupeds, including animals nourished 

 by every variety of food, and exercising very different powers of 

 progression, yet exhibiting a remarkable uniformity in their mode of 

 reproduction. In all the genera included in this family, the uterus 

 is double; in most of them the vagina is also double ; and there is 

 always a single cloacal outlet for the excrementitious substances, and 

 the products of generation. There is a corresponding uniformity in 

 the male organs, which are bifurcated at the extremity, and have a 

 double groove for the transmission of the semen ; and the male has 

 not only marsupial bones, similar to those of the female, but also a 

 muscle, similar to that which surrounds and compresses the mammary 

 gland in the female, winding round these bones like pulleys, and act- 

 ing as cremasters for the retraction and compression of the testes. 



A minute description is then given of the results of the dissection 

 of the impregnated uterus of a kangaroo, which was obtained by Mr. 

 George Bennett, during a short residence in New South Wales, and 

 which, together with the impregnated uteri of the Ornithorhynchus 

 and other valuable specimens, were sent to the Museum of the Royal 

 College of Surgeons. The membrane corresponding to the chorion, or 

 external envelope of the foetus, was found not to have a vascular struc- 

 ture, and not to adhere in any part to the surface of the uterus ; 

 neither was there any appearance of a placental or of a villous struc- 

 ture. It adhered internally to a vascular membrane, into which the 

 umbilical stem of the foetus suddenly expanded, and which terminated 

 in a well-defined ridge, formed by the trunk of a terminal blood-vessel. 

 The three omphalo-mesenteric, or vitulline vessels, were traced, from 

 the umbilical cord into the abdomen, where they terminated in the 

 usual manner; namely, the veins in the vena porta?, and the artery 

 in the aorta. Hence it was apparent that the membrane on which 

 they ramified, corresponded to the vascular layer of the germinal mem- 

 brane, which, in oviparous animals, spreads over the yelk, or to the 

 umbilical vessel of the embryos of ordinary mammalia. The ventri- 

 cles of the heart were completely joined together, and bore the same 

 proportions to each other as in the adult ; a perfection of structure 

 which is not observed in the embryos of ordinary mammalia at a cor- 

 responding period of developement. The lungs were equal in size to 

 the heart, and were of a spongy texture, and full of red blood; their 

 precocious developement, compared with that of the abdominal or di- 



