42 . [April, 



the whole number. As soon, however, as the young were contained in the 

 pouch, I received more females than males. 



February 14th, 1848. — Dissected a small female that had been captured six 

 days before. She proved impregnated, but in a much earlier stage of develop- 

 ment than the one I examined three days ago. On opening the uterus, I found 

 five on one side and seven on the other. These were nearly the size of a garden 

 pea, and resembled pellucid vesicles. Under a microscope the germinal mem- 

 brane represented a cellular structure as in olher animals. The corpora-lutea 

 corresponded with the number of ova. 



The manner in which tiie act of copulation is effected is no longer a subject of 

 conjecture, although I have not personally observed it. An intelligent coloured 

 man in whose veracity I place great confidence, was requested five years ago to 

 watch this process. He assured me that he had observed the female receiving 

 the embraces of the male while lying on her side. Within the last few weeks. 

 Dr. Middleton Michel of this city, an intelligent and close observer, who has 

 devoted much time to the investigation of this subject, has observed this process 

 with two female opossums which he has preserved in a domesticated state. He 

 informs me that they received the male whilst lying on their right side. 



From various observations I have made for the last three years, I had set 

 down the period of gestation in the opossum at 17 days. I received a female, 

 said by the servant to have been captured in the act of copulation. She pro- 

 duced her young on the seventeenth day. I had, however, placed her with a male 

 that I kept in confinement at the time ; but she exhibited such a savage temper 

 towards him, that for the sake of peace, I was compelled to separate them after 

 three days. Dr. Michel, however, informs me that a female in his possession, 

 produced young on the fourteenth day. Although I was at first confident that the 

 true period was 17 days, I think it probable that from the superior advantages 

 Dr. Michel has possessed with his animals in a state of domestication, he may 

 have approximated nearer to the true time than myself. 



In the second volume on American Quadrupeds, now in the course of publica- 

 tion, the history of this animal will be treated more in detail. 



Further Observations on the Generation of the Opoxsiim. 



By the Rev. Dr. Bachman. 



February I5th, 1848. — On the morning of this day I received five female 

 opossums from the country, three of whom I was informed by Col. Hail, (who 

 zealously and successfully interested himself in procuring specimens for my 

 examination), had produced young in the box in which they were confined, a day 

 or two previous to their having been sent. Their several pouches contained 

 eight, nine, and eleven young. There were two, as he informed me, in the stale 

 in which I was anxious to obtain them ; as they had not yet produced their 

 young. On examination, however, 1 discovered that one of the two had evi- 

 dently brought forih amid the joltings consequent on her conveyance from the 

 country. Five young were in the pouch. I observed, on examination, that a 

 sixth was lying at the bottom of the box, and was still living. Supposing it 

 possible that all the young had not been excluded, I concluded to sacrifice the 

 mother; and was repaid for an apparent cruelty, exercised very reluctantly, by 



