140 AUSTRALIAN NATURAL HISTORY. 



only one premolar (tlie tliird) above and below in eacb ramus. 

 In this respect the native bears approach the kangaroos on the 

 one hand and the gigantic extinct phalangers on the other. 



There is also some relationship with the wombats in the shape 

 of several bones, and in the occasional reduction of the upper 

 incisor teeth to four, or even a single pair. The second and 

 third upper incisors are small, and sometimes either missing or 

 lost at an early age. Many individuals examined by me had only 

 two incisors above in each ramus and two below, a fact which I 

 desire to mention, as it niay lead to further investigation. The 

 upper grinders of the native bears are very broad, almost square, 

 and provided \\ith four sharp tubercles, the lower ones are more 

 compressed. The undeveloped premolar of certain large extinct 

 phalangers resembles the molars of the native bears, and young 

 individuals of these again possess bones which bear a great like- 

 ness to those .of full-grown Diprotodons. To this resemblance I 

 shall refer again farther on. 



Sub-Family Diprotodontidce. 



The Diprotodons were gigantic animals, with teeth constructed 

 on the phalanger type, that is, six incisors above, and a pair 

 below, without canines, the premolar generally present but often 

 shed at an early age, molar teeth with a two-ridged crown divided 

 by a valley and with rims or talons in front ; the enamel either 

 rugged and of a worm-eaten appearance or smooth. 



These animals form two groups, the Zygomaturi and the Dip- 

 rotodons proper, and at present they are not well understood by 

 naturalists. 



The chief diiference consists in the cutting teeth, but as the 

 mandibles and skulls are seldom found together, and as it cannot 

 be proved when so found that the one really belongs to the other, 

 we have been obliged to accept the additional genus Nototherium 

 for certain loose mandibles. Professor Owen claims the only 

 perfect skull of the genus Zygomaturus ever discovered, which 

 was described by the late Mr. W. S. Macleay as belonging to his 

 genus Nototherium — but this claim, as the lawyers say, has been 

 disallowed. An exhaustive review of all Professor Owen's papers 

 on Australian Possil Eemains has lately been published in the 

 pages of the Sydnei/ Mail, and to this I refer for particulars. 

 Our Zygomaturus skull retains its incisor teeth, and I possess the 

 fractured portion of the upper jaw of another Zygomaturus, 

 containing the first incisor, the broken off second, and the alveolus 

 of the third. These fragments were discovered by Dr. Creed, 

 near Scone, and formed part of a skull which unfortunately broke 

 to pieces when touched. The first of these teeth is figured on 

 plate No. 2. The principal difierence between the two genera is 

 as follows : — 



