10 



bize to these and Myrmecobius. The exact condition of the incisors 

 and canines of the Thylacotherium has not yet been displayed in 

 the fossil jaws which have been discovered. 



Saltatoria. 



Genus Perameles (Bandicoots). 



Incisors g-^ ; canines |^ ; prcemolares 3-=^ ; molares ^ : = 48. 



This dental formula characterizes a number of Rat-like Insectivora 

 commonly known in Australia by the name of Bandicoots ; the hind 

 legs are longer and stronger than the fore, and exhibit in a well- 

 marked manner the feeble and slender condition of the second and 

 third digits counting from the inside, and the sudden increase in 

 length and strength of the third and fourth digits, which are chiefly 

 subservient to locomotion : the mode of progression in the Bandi- 

 coots is by bounds ; the hind and fore feet being moved alternately 

 as in the Hare and Rabbit ; and the crupper raised higher than the 

 fore quarter. The teeth which offer the greatest range of variation 

 in the present genus are the external or posterior incisors and the 

 canines : the molares, also, which originally are quinque-cuspi- 

 date, have their points worn away, and present a smooth and obhque 

 grinding surface in some species sooner than in others. 



The Bandicoots which approach nearest to the Myrmecobius in 

 ihe condition of the incisive and canine teeth are the Perameles 

 obesula and P. radiata. There is a slight interval between Ijhe 

 first and second incisor, and the outer or fifth incisor of the upper 

 jaw is separated from the rest by an interspace equal to twice its 

 ov\Ti breadth, and moreover presents the triangular, pointed, canine- 

 like crown which characterizes all the incisors oi Myrmecobius ; but 

 the four anterior incisors are closely arranged together and have 

 compressed, quadrate, true incisive crowns. From these incisors the 

 canine is very remote, the interspace being equally divided by the 

 fifth pointed incisor, which the canine -very slightly exceeds in 

 size. In Peram. nasuta the incisor presents the same general con- 

 dition, but the canines are relatively larger. 



The marsupial poucli in the Bandicoots, at least in the full-grown 

 females of Per. nasuta. Per. obesula, and Per. lagotis, has its 

 orifice directed downwards or towards the cloaca, contrariwise to 

 its ordinary disposition in the Marsupials: this direction evidently 

 relates to the position of the trunk when supported on the short 

 fore and long hind legs. In the stomach and intestines of a Per- 

 ameles obesula, I found only the remains of insects ; and in the ex- 

 amination of the alimentary canal of a Per. nasuta. Dr. Grant ob- 

 tained the same results. 



Genus Chceropus. 



The singular animal on which this genus is founded is briefly 

 noticed and figured in Major Mitchell's Austraha, (vol. ii. pi. 38. 

 p. 131.) and the individual described is preserved in the Colonial 

 Museum, at Sydney, N. S. Wales, (No> 35. of Mr. George Bennett's 



