MARSUPIALS. 381 



The smaller species of Didelphys, which are the most numerous, 

 fulfil in South America the office of the insectivorous Shrews of 

 the old Continent. The larger Opossums resemble in their habits, 

 as in their dentition, the carnivorous Dasyures, and prey upon the 

 smaller quadrupeds and birds, but they have a more omnivorous 

 diet, feeding on reptiles and insects and even fruit. One large 

 species, {Did. cancrivora) prowls about the sea-shore and lives, as 

 its name implies, on crabs and other crustaceous animals. Another 

 species, the Yapock, frequents the fresh waters, and preys almost 

 exclusively on fish. It has all the habits of an Otter ; and, in 

 consequence of the modifications of its feet, forms the type of the 

 sub-genus, Chironectes, 111. Its dentition, however, does not differ 

 from that of the ordinary Opossums. 



152. Carpophaga. — In this tribe the teeth, especially those at 

 the anterior part of the mouth, present considerable deviations 

 from the previously described formulae ; the chief of which is a 

 predominating size of the two anterior incisors, both in the up- 

 per and lower jaws. Hitherto, we have seen that the dentition 

 in every Marsupial genus has participated more or less in a car- 

 nivorous character ; henceforth it will manifest a tendency to the 

 Rodent type. 



Genus Tarsipes. — The dental formula of this genus has not been 

 accurately determined ; the molars soon begin to fall, the small 

 canines are also deciduous, the two long, procumbent incisors of 

 the lower jaw remain the longest ; besides these only one small 

 molar was present in each ramus, in the first specimen described. 

 The inferior incisors are opposed to six minute incisors above, 

 which are succeeded by a small canine and some small molars, 

 but these were reduced to a single tooth on each side in M. Gervais' 

 specimen. This was kindly submitted by that acute observer, the 

 founder of the present Genus, to my examination, and the trans- 

 parency of the dental tissue permitted the tubular structure to be 

 examined by the microscope with transmitted light : it resembled 

 in the degree of divergence of the tubuli calcigeri the dentine of the 

 Mole and other small Insectivora. 



The Genus Tarsipes seems, in fact, to link the Myrmecobius 



