327 



The London, Edinburgh, and Dublin Philosophical Magazine, and 

 Journal of Science. Third Series. Nos. 199, 200. February 

 and March, 1847. 8vo. 



Comptes Rendus Hebdomadaires des Seances de I'Academie des Sci- 

 ences; par MM. les Secretaires Perpctuels. Tome XXIII. Nos. 

 19 to 26, inclusive. November 9, to December 28, 1846. 4to. 



The Committee (Drs. Hays, Bache and Condie), to whom 

 had been referred the memoir of Dr. Charles D. Meigs, upon 

 the reproduction of Didelphis Virginiana, read 19th March, 

 1847, reported, recommending its publication in the Transac- 

 tions of the Society, which was ordered accordingly. 



Professor vixen's paper on the reproduction of the kanguroo and 

 the wombat, has left certain points still unsettled as to the reproduc- 

 tion of the marsupials ; and MM. Milne Edwards and Pouchet, in 

 their works, have left uncleared up several points, which it is the ob- 

 ject of Dr. M.'s paper to explain. 



The terms foetus and embryo cannot properly be applied to the 

 young of the didelphis while in the pouch; since, when first placed 

 in the marsupium, the young opossum is endowed with all the attri- 

 butes of a mammiferous quadruped in the full enjoyment of a real 

 warm-blooded respiratory and digestive existence. None of the au- 

 thors on this subject appear to have investigated the state of the early 

 young; and the most vague and incorrect notions still prevail as to 

 their condition. 



On the 18th February, 1847, a light snow having fallen, the 

 tracks of two opossums were followed on the 19ch, over the snow, to 

 the trunk of a hollow tree, wherein they had concealed themselves, 

 and from which were taken a full grown male and female didelphis. 

 It was supposed, from the appearance of the testes in the male, and 

 the monotrem of the female, that the animals had retired for the rut, 

 as they are rarely found in company at other seasons. 



On the 27th February they were brought to me, and I carefully 

 examined the marsupium, but could discover no trace of any mam- 

 mary development of the base of the delicate nipples. February 

 28th, no change was discovered by inspection or careful palpation 

 of the pouch. On Monday, March 1st, and on Tuesday, the 2d, 

 there was not the least sign of change in the pouch. On Wednes- 

 day, the 3d, the mammary glands were visibly and palpably en- 

 larged. On Thursday, 4th, still larger. On Friday, 5th, hard and 



