158 



MEMOIR ON THE REPRODUCTION OF THE OPOSSUM. 



capture. And now, if we may justly suppose that the fecundation occurred on or about 

 the 19th of February, we have an inference as to a uterine gestation, of sixteen or 

 seventeen days. 



As to the value of this computation I leave naturalists to judge; begging them to bear 

 in mind the extreme rapidity of the mammary development; which commenced on Wed- 

 nesday, the 3d, and was completed certainly on Sunday, the 7th of March — four days. 

 It seems that so rapid a development of the milk glands ought to be taken as evidence, if 

 not proof, of a rapid uterine gestation. 



The observation is useful, as settling at least, the question, of one of the reproductive 

 seasons — which is in February, in this instance, and probably in the two formerly men- 

 tioned. 



Mr. Owen's observation of the gestation of the kangaroo showed, that it came into 

 the pouch on the thirty-ninth day after the sexual congress, which was accurately noted, 

 and which, having been effected thrice in a short space of time, produced only one fetus. 



Mr. Owen does not mention the state of the mammary glands, and seems to have 

 examined only the nipples, which are much less to be depended upon, as signs of gesta- 

 tion, than the glands themselves. 



In my opossum I counted thirteen fetuses, all of them busily engaged in sucking, and 

 freely using their fore-arms, with which they held on to the fur of the pouch — so that to 

 open the sphincter was to see a busy scene of motions. 



The figure which I have caused to be made shows pretty well the appearance of the 

 pouch, whenjield open with two fingers, on the twelfth day. 



