OF NEW HOLLAND. 343 



means of hands, comprises the genera Didelphis and Cheiro- 

 nectes, with didelphoid teeth ; and Phalangista, Petaurus, 

 and Phascolarctos, with macropoid. 



2. The digitigrade form, in which the functions of pre- 

 hension and manipulation are very much impaired, or altoge- 

 ther absent. The hind feet are without opposable thumbs, 

 which, however, are sometimes represented by a small, mo- 

 tionless tubercle ; the animals tread only on the toes in walk- 

 ing, and their pace is confined to the surface of the earth. — 

 All are characterised by the didelphoid system of dentition, a 

 regimen principally confined to animal substances, [and an 

 entire absence of cacum]. 1 This family, which, from the na- 

 ture of their pace, I shall denominate Digitigrades, 2 com- 

 prehends the genera Thylacinus, Dasyurus, Phascogale and 

 Myrmecobius. 3 



3. The saltigrade form, in which the posterior extremities 

 so immeasurably exceed the anterior in length, as to preclude 

 the ordinary mode of progression on all fours, and to compel 

 the animals to proceed by a series of successive springs, some- 

 times from the long hind legs only, sometimes from the hind 

 to the fore legs, as in the hares and rabbits. The toes of the 

 fore feet are separate and prehensile, and the animals enjoy 

 perfect powers of manipulation ; but the conformation of the 

 hind toes is altogether unique among mammals. The thumb 

 is tuberculous, or altogether wanting ; the two following toes 

 are small, slender and inclosed in the same skin, being mark- 

 ed externally only by their double claw ; the ring finger is 

 the largest of all, of a size altogether disproportioned to the 

 other toes, and armed with a powerful triangular claw ; and 

 the last, or outer finger is of intermediate size, and provided 

 with a similar claw to that just described. The dentition 

 comprehends examples of both the systems above character- 

 ised ; the food of some genera is consequently mixed, though 

 in all cases it is principally composed of vegetable substan- 

 ces, and a ccecum, sometimes of very large dimensions and 

 complicated form, is invariably present. This family, which 

 I shall call Saltigrades, 2 contains the genera Macropus and 

 Hypsiprymnus with macropoid teeth, and Perameles and 

 Chceropus* with didelphoid. 



4. The plantigrade form, which is confined to the single 

 genus Phascolomys. The toes here are short, rigid and unpre- 

 hensile, well adapted for burrowing, and without any power of 

 manipulation. The animal treads on the entire sole of the 



1 1 have inserted this fact on the authority of Dr. Grant. 

 3 and 4 These two genera have been discovered since the paper was written, 

 and are now inserted for the first time. — W. O. April, 1839. 



