Prof. Owen on the Reproduction of the Opossum. 325 



marsupial young, begun on Wednesday the 3rd of March, and com- 

 pleted by Sunday the 7th, which is four days. Hence it is clear 

 that the notion heretofore entertained, that the embryo makes the 

 teat wherever it happens to take hold, is unfounded, the preparation 

 being as complete as in any other mammal. 



M The uterine gestation probably terminated on the night of 

 Saturday March the 6th, or the morning of Sunday the 7th. The 

 rut probably continued as late as the 18th or 19th February, which 

 is seventeen or eighteen days ; possibly the impregnations may have 

 been a few days earlier than the said dates. 



" The observation settles at least the question as to one of the 

 reproductive seasons, which in this case was February. 



" In Mr. Owen's observation on the kangaroo, the uterine gesta- 

 tion lasted thirty-nine days ; but the kangaroo is a large animal in 

 comparison ; the opossum rarely being more than fifteen or sixteen 

 pounds in weight. 



" Mr. Owen does not mention the preliminary condition of the 

 mammary glands in the kangaroo. 



" Thirteen young opossums were attached to as many nipples, all 

 strongly adhering, and busily employed in sucking the milk. 



" They moved the fore-arms, and paws, and heads, very freely ; so 

 that to open the sphincter marsupii was to disclose a very lively scene. 



" They were of a deep rose tint, and without hair. 



" They were of equal size. I pulled one off from the nipple ; and 

 the attachment was so strong, that I expected to tear the body in 

 two before I disengaged the mammilla from the stomal pore in which 

 it was engaged. There was no bulb at the end of the nipple after 

 the detachment of the young one. 



"No blood about the mouth or on the nipple followed the sepa- 

 ration. 



" It was removed at 40 minutes past 7 p.m. It weighed exactly 

 three grains and a half. 



" From the snout to the end of the tail it was eight-tenths of an 

 inch long. 



" Laid in a watch-glass, it moved freely round and round the glass, 

 and turned over on one side and the other. 



" Examined by a lens, it respired by two nostrils and by the mouth. 

 It died at ten minutes past nine o'clock, which was one hour and 

 twenty-nine minutes after its separation, though exposed for some 

 time to the cold air of the street. 



" The tongue was apparently equal to one-third the magnitude of 

 the head — milk-white, grooved so as to embrace half the cylindrical 

 oircumference of the teat, which was pressed, as to its other half, 

 against the vault of the palate. The mouth was a pore, which I 

 could not distinctly discern without a lens ; the cavity of the mouth 

 spacious. The diaphragm strong. 



" The heart, in its pericardium, large and powerful. The liver very 

 large. The stomach filled with milk vesicles, examined under the mi- 

 croscope ; the intestinal convolutions distended with milk and chyle, 

 stained yellow with bile ; the bladder of urine filled with fluid. 



