MARSUPIALIA. 101 



surfaces, as in the Rodentia, of which this family is generally 

 considered to be the Marsupial analogue. The molars are strongly 

 curved, and composed each of two parallel lobes. The general 

 form is stout and squat, and the tail rudimentary, consisting of 

 only from 8 to 12 vertebrae, while the Phalangers have from 25 to 

 31. The feet show a slight tendency towards a syndactylous 

 structure. All the three known species are represented in Case 24, 

 Div. A, by skeletons and skulls. 



The Bandicoots (Peramelidte) present us with the first instance 

 of a " polyprotodont " carnivorous dentition, that is with many 

 incisors in the lower jaw, and with the lower and upper canines 

 well developed, and suited for seizing and holding small mammals, 

 birds, worms, beetles, &c. Their dental formula is I. , C. -}, 

 Pm. f, M. x2 = 48. On the other hand, their feet show a 

 close resemblance to those of the diprotodont Kangaroos, so that 

 these animals are in some measure intermediate between the two 

 great groups of Marsupials. 



The DasyuridcK are the most highly developed carnivorous Mar- 

 supials, representing in this Order the true Carnivora of the 

 placental series. The best known is the Thylacine or Tasmanian 

 Wolf (Thylacinus cynocephalus) , whose skull strikingly resembles 

 that of one of the Dog tribe. Its dentition is I. |, C. ^-, Pm. |, 

 M. \ x 2 = 46. the teeth being sharp and cutting, and well suited 

 to its predatory habits. Its feet are of the normal mammalian 

 structure, and the marsupial bones represented by unossified 

 cartilages only. 



The Dasyures (Dasyurus) are smaller carnivorous forms, which 

 correspond in their habits to the weasels, martens, and other small 

 placental Carnivores, while the still smaller Phascologales and 

 SminthopsiSj which range from the size of a rat to that of a mouse, 

 and live on insects, worms, &c., represent the placental Insectivora. 

 Their teeth are numerous, small, and covered with sharp pointed 

 cusps. Myrmecubius fasciatus is remarkable for having the largest 

 number of teeth known in any heterodont mammal, its dentition 

 being I. f , C. }, Pm. f , M. f x 2 = 54. The teeth are small 

 and sharply cuspidate. Its external features and its habits have 

 already been referred to (p. 57). 



The Didelphyida, or Opossums, natives of America, resemble 



