502 



CHORD ATA. 



characters, be recognised at once by the presence of more 

 than three pairs of upper incisors. The canines are large 

 and prominent and the molars are cusped. In other words, 

 the Folyprotodontia have a typical carnivorous dentition, and 

 all are flesh- or insect-eaters. They are aquatic, cursorial, 

 fossorial, or arboreal. 



Family I. — Didelphidae comprise the Opossums, found in the 

 warmer regions of America. They are usually "true arboreal" and 

 hence have an opposable hallux or big toe, the other four toes being 

 nearly equal and each bearing a claw. The Yapock, however, is 

 aquatic and has webbed feet. The opossums vary in size and colora- 

 tion and there is a large number of species. 



Fig- 347- — ^Jaws and Teeth of the Opposum {Didelphys). 



Note the five upper and four lower incisors, long canines, sharp cusped molars 

 with four true molars ( ^-?4\ ^j^ essentially carnivorous dentition. 

 \4i34/ 



Family II. — Dasyuridse comprise a number of carnivorous and 

 insectivorous animals found in the Australian region. They vary in 

 size from the Tasmanian wolf (Thylacintis) to the little mouse-like 

 Phascogale. The Tasmanian "devil'' ( Sarcophilus ) has the fossorial 

 habits of the badger, and the Dasyures (Dasynrus) are much like small 

 civets. The Banded Anteater ( Myrmecobius) has a great number of 

 small teeth and it has no pouch. 



Family III. — Peramelidae comprise a number of small animals, 

 the Bandicoots, found only in the Australian region. They are " small- 

 flesh " eaters (worms, insects and occasionally vegetable diet). 



They are interesting for two structural features, viz. , the presence of 

 an allantoic placenta and the syndactylic condition of the hind-foot (see 

 Diprotodontia). The " Native Rabbit" ( Peragale) is fossorial. 



Family IV. — Notoryctidae is made for the curious metatherian 

 mole ( Notary ctes). A true fossorial type found in the sandy districts 

 of central Australia. Its structure is adapted for rapid bun owing 

 and in this respect shows a likeness to the fossorial armadillos and 

 to the mole. 



