Zoological Society. 121 



simple structure, and are arranged in a regular semicircle without 

 any middle interval. The six incisors of the lower jaw are simi- 

 larly arranged but have thicker crowns than the upper ones ; the 

 canines present the same or even a greater relative development 

 than in the Thylacine. In an extinct species of Dasyurus they 

 present the same form and relative properties as in the Leopard. 

 The spurious molares have two fangs and a pointed compressed 

 triangular crown with a rudimental tubercle at the anterior and 

 posterior part of its base. The grinding surface of the true molares 

 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 ex- 

 ternal one being the longest ; the second and third molares 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 tubercle of the posterior molar of the lower jaw 

 is divided into two small cusps. 



The carnivorous character of the previous dentition is most 

 strongly marked in the Ursine Dasyure, or Devil of the Tasmanian 

 colonists, the largest existing species of the genus, and a most 

 pestilent animal in the poultry yard or larder. 



Genus Phascogale. 



Incisors *—; canines £=| ; praemolares ^ ; molares ^ : = 46. 



In the present dental formula may be discerned a step in the 

 transition from the Dasyures to the Opossums, not only in the in- 

 creased number of spurious molares, but also in shape and pro- 

 portions of the incisors. In the upper jaw the two middle in- 

 cisors are longer than the rest, and separated from them by a 

 brief interval; they are more curved and project more forward. 

 The three lateral incisors 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 

 molares present a similar form, but the third is much smaller and sim- 

 pler than the two preceding ones. The true molares resemble in 

 their structure those of the Dasyures. The general character of 

 the dentition of these small Marsupials approximates to the insecti- 

 vorous type in the Shrew, Hedgehog, &c., among the placental 



Ann. Nat. Hist. Vol.4. No. 22. Oct. IS39. k 



