11 



Catalogue). It would appear that the two outer toes of the fore- 

 foot, which are always very small in the true Bandicoots, are en- 

 tirely deficient in the Chcsropus, unless some rudiments should exist 

 beneath the skin ; at all events only two toes are apparent extern- 

 ally, but they are so armed and developed as to be serviceable for 

 burrowing or progression. The inner toe is wanting on the hind 

 foot. Dental formula : 



Incisors ^^ ; canines^^J ; prsemolares g^ ; molares —^ : = 46. 



All the teeth are of small size ; the canines resemble the spurious 

 molares in size and shape, and these are separated at intervals as 

 in Mxjrmecobius . The marsupium opens downwards in the Charopns, 

 as in the true Bandicoots. The species described has no tail. The 

 genus would seem by its dentition to rank between Myrmecobius and 

 Perameles. Its digital characters are anomalous and unique among 

 the Marsupialia. 



SCANSOKIA. 



DidelphidcB, Opossums. 



These Marsupials are now exclusively confined to the American 

 Continents, although the fossil remains of a small species attest the 

 former existence of the genus DidelpMs in Europe contemporaneously 

 with the Palseothere, Anoplothere, and other extinct Pachyderms 

 whose fossil remains characterize the Eocene strata of the Paris 

 Basin. The dental formula of the genus Didelphis is. 



Incisors- 5^^ ; canines ^ ; pr£emolares|^ ; molares |^ : =50. 



The Opossums resemble in their dentition the Bandicoots more 

 than the Dasyures, except in the structure of the molares. 



The two middle incisors of the upper jaw are more produced than 

 the others, from which they are separated by a short interspace. 

 The canines are well developed, the upper being always stronger 

 than the lower. The false molares are simply conical ; the true 

 ones beset with sharp points, which wear down into tubercles as the 

 animal advances in age. 



In the type of the subgenus Cheironectes, besides being web- 

 footed, the anterior extremities present an unusual development 

 of the pisifoi-m bone, which supports a fold of the skin, like a 

 sixth digit; it has indeed been described, as such, by M. Tem- 

 minck ; this process has not of course any nail. The dentition 

 of the Yapock resembles that of the ordinary Didelphis. All the 

 Opossums have the inner digit of the hind foot converted by its 

 position and development into a thumb, but without a claw. The 

 hinder hand is associated in almost all the species with a scaly 

 prehensile tail. 



In some of the smaller Opossums the subabdominal tegumentary 

 folds merely serve to conceal the nipples, and are not developed into 

 a pouch ; the young in these adhere to the mother by entwining 

 their little prehensile tails around hers, and cling to the fur of the 

 back ; hence the term dorsicjera applied to one of these Opossums*. 



* Few facts vvould be more interesting in the present branch of zoology 

 tlian the condition of the new-born young, and their degree an'd mode of 



