814 DR. .1. MURIE ON PHASCOLOMYS PLATYRHINUS. [JuHB 27, 



most like each other in form and size : in two specimens the first 

 measured 5^ inches iu its long diameter, the second 6" ; but in P. 

 platyrhinus it is considerably the stronger and thicker, the shaft 

 being somewhat compressed from before backwards, whereas it is 

 nearly round in wombat. 



The length of the femur in P. latifrons is 5^^ inches, but, although 

 shorter tlian in P. wombat, it is much stouter ; the shaft is also 

 straighter. The prominent antero-posteriorly compressed outer ridge, 

 which extends downwards from the great trochanter, so as to form a 

 kind of third trochanter in P. wombat and P. platyrhimis, is absent 

 in P. latifrons ; a roughening behind the shaft merely represents this. 



Tibia and Fibula. — P. iilatyrhinus and P. wombat again approxi- 

 mate in the form of the tibia ; it is much the broader antero-poste- 

 riorly in the former, while the shaft is straighter in the latter. The 

 shaft of P. latifrons is still more laterally com]>ressed ; and about 

 the centre of the shaft the anterior edge is slightly bent outwards, 

 which also takes place in a less degree in P. platyrhinus, but not in 

 P. wombat. The lengths of these bones are respectively 4"'7, 4"'5, 

 and 4"'4. The articulating surfaces in P. latifrons are abruptly flat- 

 tened and spread out, but they are more sloping in the other species. 



The tibia seems to be reversed, and differs in length, being j\ 

 of an inch shorter in P. latifrons ; and the shaft is rather more 

 compressed laterally ; at least it is broader and stronger antero-poste- 

 riorly, the strong sharp ridge continued in front, the head rising to 

 be a roughened protuberance in the upper part of the middle one- 

 third of the shaft, as Owen has described in the Koala*. 



The fibula is of about equal length in P. wombat and P. latifrons, 

 but the shaft is straighter and stouter in P. latifrons ; the inter- 

 osseous space is also wider in it, giving a greater breadth for the 

 origin of the anterior muscles of the leg. 



Metatarsal and Phalangeal Bones. — In the hind foot P. platy- 

 rhinus and P. wombat agree in having the index digit somewhat 

 shorter than the third, and in having its proximal phalanx decidedly 

 shorter than the metatarsal ; whereas in P. latifrons the index is 

 the longest, and has its proximal phalanx and metatarsal of almost 

 equal length. This circumstance gives the hind foot of P. latifrons 

 quite a characteristic shape. 



Conclusion. 



In reviewing the observations contained in the present paper it is 

 necessary to take into account the results of my former communica- 

 tion on the Hairy-nosed Wombat and the species of Phascolomys 

 generally. 



What the axial and appendicular skeletons further show is, that 

 P. wombat and P. platyrhinus are closely related in several parti- 

 culars, and that P. latifrons differs decidedly from them both. 



Phascolomys platyrhinus, it would seem, .can only be recognized 

 as specifically distinct from P. wonihat in a zoologic.il sense. 



Size and colour, which last varies consideraljly, point out a de- 

 parture from the type of P. wombat. 



* Trans. Zool. Soc. vol. ii. p. 405. 



