MARSUPIALIA. 



259 



Genus DASYUHUS. (Fig. 81.) 



Fig. 81. 



Dasyunts Ursinus, one-third natural sixe. 



44 11 

 Incisors r ; canines praemolars 



O O A 1 



22 44 



1^ J molars 4^4" : ~ * 2 " 



The eight incisors of the upper jaw are of 

 the same length and simple structure, and are 

 arranged in a regular semicircle without any 

 median interval. The six incisors of the lower 

 jaw are similarly arranged, but have thicker 

 crowns than the upper ones. The canines 

 present the same or even a greater relative de- 

 velopment than in the Thylacine : in an extinct 

 species of Dasyurus* they had the same form 

 and relative proportions as in the Leopard. 

 The spurious molars have a pointed com- 

 pressed triangular crown with a rudimental tu- 

 bercle at the anterior and posterior part of its 

 base. The grinding surface of the true molars 

 in the upper jaw is triangular; the first presents 

 four sharp cusps, the second and third each 

 five, the fourth, which is the smallest, only 

 three. In the lower jaw the last molar is 

 nearly of equal size with the penultimate one, 

 and is bristled with four cusps, the external one 

 being the longest : the second and third molars 

 have five cusps, three on the inner and two on 

 the outer side ; the first molar has four cusps : 

 these are all sharply pointed in the young 

 animal, in which the posterior tubercle of the 

 posterior molar in the lower jaw is divided 

 into two small cusps. 



The carnivorous character of the above den- 

 tition is most strongly marked in the Ursine 

 Dasyure or Devil of the Tasmanian Colonists, 

 the laigest existing species of the genus, and 

 a most pestilent animal in the poultry-yard or 

 larder. 



Genus PHASCOGALE. (Fig. 82.) 



Phascogale penicillata. 



* Dasyunts laniarius, Owen : the fossil remains 

 of this species were discovered with tho^e of two 

 gigantic species of Kangaroo in the bone-caves of 

 Wellington Valley, Australia, by Major, now Sir 

 Thomas, Mitchell. 



Incisors 



44 



^~^ ; canines 7~p praemolars 



33 44 



3 ; mo'ars : = 



In the present dental formula may be dis- 

 cerned a step in the transition from the Da- 

 syures to the Opossums, not only in the in- 

 creased number of spurious molars, but also 

 in the shape and proportions of the incisors. In 

 the upper jaw the two middle incisors are 

 longer than the rest, and separated from them 

 by a brief interval ; they are more curved and 

 project more forward. The three lateral in- 

 cisors diminish in size to the outermost. The 

 middle incisors of the lower jaw also exceed 

 the lateral ones in size, and project beyond 

 them but not in the same degree, nor are they 

 separated from them by an interval, as in the 

 upper jaw. The canines are relatively smaller 

 than in the Dasyures. The spurious molars 

 present a similar form, but the third in the 

 lower jaw is smaller and simpler than the two 

 preceding ones. The true molars resemble 

 those of the Dasynres. 



The general character of the dentition of 

 these small predatory Marsupials approximates 

 to the insectivorous type, as exemplified in 

 the Shrew, Hedgehog, &c. among the placental 

 Mammalin, and corresponds with the food and 

 habits of the species which thus lead from the 

 Sarcophagous to the Entomophagous tribes. 



The interval is further diminished by a 

 lost marsupial genus which forms one of the 

 ancient Mammalia that have rendered the 

 oolitic formations at Stonesfield so celebrated. 

 This genus, which I have called Phascolothe- 

 rtum, presents the sarre numerical dental formula 

 as in Phaxcogale, viz. 



Incisors 



? 



33 or 44 ; 



canines 



praemolars 



3 3 ' 



molars 



44 ' 



But the incisors and canines are separated by 

 vacant interspaces, and occupy a large pro- 

 portional space in the dental series : the true 

 molars resemble those of Thylacine. 



Tribe II. ENTOMOPHAGA. 



This is the most extensive and varied of the 

 primary groups of the Marsupial order. In 

 the system of Cuvier, the species of this tribe 

 are united with those of the preceding- to form 

 a single group characterized by the presence of 

 long canines and small incisors in both jaws : 

 but in most of the Entomophagous genera of 

 the present classification, the canines present a 

 marked inferiority of development, and the 

 species are consequently unable to cope with 

 animals of their own size and grade of organ- 

 ization, but prey, for the most part, upon the 

 smaller and weaker classes of invertebrate 

 animals. Their intestinal canal is complicated 

 by a moderately long and large coecum; and 

 while, in the Sarcophaga, the feet are con- 

 structed upon the plan of those of the ordinary 

 placental Digitigrades, they offer in the pre- 

 sent tribe a variely of well-marked modi- 



s 2 



