Mammalia: Classification 



::5:5 



Fig. 538. Caenolesfes, a Bolivian marsupial. (Courtesy, American Museum of Nat- 

 ural History, New York.) 



Ch 



M 



ammalia 



Subclass i. Monotremata 



Only two existing Families: 



Ornithorhynchidae, containing the one Genus, Ornithorhyn- 

 chus, the duckbill. 



Echidnidae, including two or three species of Echidna, the 

 spiny anteater. Some classifications recognize two Genera: Echidna 

 (or Tachyglossus) and Proechidna (or Zaglossus). 



Monotremes occur only in Australia, Tasmania, and New Guinea. 



Subclass ii. Marsupialia 



Order 1 : POLYPROTODONTIA. Dentition of carnivorous type 

 — many small incisors (four or five pairs in upper jaw, fewer in lower) 

 of nearly equal size; large canines; sharp-pointed molars. 



Examples: Opossum (Didelphis) whose dental formula is 



i -r, Ct, p^, m-; dasyure, the "Australian cat" (Dasyurus); the 



"Tasmanian wolf'' (Thylacinus); the burrowing bandicoot 

 (Perameles); and "marsupial mole" (Notoryctes) : (Figs. 534-537, 

 592). 



Order 2: CAENOLESTOIDEA. Dentition numerically resembles 

 that of polyprotodonts, but, in type of differentiation, more like that of 

 diprotodonts. Small, rodent-like Caenolestes (Fig. 538). 



