EX TIXC T FA Mil IKS 



171 



Extinct Families. 



Hero may be noticed two genera of extinct Marsupials, the remains 

 of which have been found in the Pleistocene deposits of Australia, 

 which agree with the MacropodidcB and the Phalange/idee in having 

 I incisors, those of the lower jaw being very large and proclivous. 

 As the whole of their structure, especially that of the hind feet, is 

 not yet known, their precise affinities cannot he determined. 



DiprotodonJ 1 — Dentition : i f, c #, p \, m •£- ; total 28. The first 

 upper incisor very large and sealpriform (Fig. 56). True molars 

 with prominent transverse ridges, as in Macropus, but -wanting 

 the longitudinal connecting bridge. Anterior and posterior limbs 

 less disproportionate than in the Kangaroos. Humerus elongated, 

 and differing from that of nearly all Marsupials in the absence of an 



Fig. 56. — Left lateral aspect of the skull of Diprotodon australis; from the Pleistocene of 

 Australia. 7 V, natural size, i, Incisors ; p, premolar ; m, molars. (After Owen.) 



entepicondylar foramen. The palate is fully ossified, and there is 

 no pit or perforation in the masseteric fossa of the mandible. I), 

 australis is the largest known Marsupial, being fully equal in bulk 

 to a Rhinoceros. It may be regarded as the type of a family — 

 Diprotodontidce — having affinity on the one hand with the Phalangers 

 and on the other with the Kangaroos. 



XutofJir r'ui in.' 1 — Represented by a species of somewhat smaller 

 size than the type of Diprotodon, with a shorter skull, in which the 

 zygomatic arches are very wide and the nasals curiously expanded 

 at their extremities. The mandibular symphysis is ankylosed ; 



1 Owen, in MitchelVs Eastern Australia, 2d ed. vol. ii. p. 362 (1838). 

 2 Owen, Cat. Mamm. a ml Arcs, Mas. /,'. Coll. Surgeons, p. 314 (1845). 



