812 DK. J. iMt Klli ON PHASCOLOMYS PLATYRHINUS. [Juiie 27, 



sharper-pointed inwardly curved process. The free border of the 

 spine is not thick posteriorly ; but it becomes equal to that of P. 

 'platyrhinus and almost broader than that of P. icomhat at the pos- 

 terior half of the acromion process. 



The coracoid process is bent downwards and inwards, as usual in 

 P. wombat ; but the groove where the biceps tendon is lodged is in 

 P. latifrons shallower. Towards the neck it rises with a convexity, 

 and with a roughened elongated pit for the insertion of the tendon 

 of the biceps. 



In the Common Wombat the supra- and infraspinous fossae are 

 very flat ; whereas in P. latifrons and, to a lesser extent, in P. platy- 

 rhinus they are concave, more especially the infraspinous fossa. The 

 subscapular surface of the bone in Wombat has shallow ridges and 

 furrows, but in the other species these are much more marked. 



Clavicle. — In the Platyrhine and Common Wombats this bone 

 equally has a double curvature, being by far the stronger and more 

 grooved in the former animal. 



In the Hairy-nosed Wombat the clavicles are somewhat straighter 

 than in the others. Of about equal length to those of the Common 

 species, they, in consequence of their straightness and also more in- 

 ward projection of the acromion processes, give an apparently greater 

 breadth of chest to the Hairy- nosed species. 



Humerus. — The humerus oiP.platyi-hiyius is 4^ inches long, of P. 

 latifrons 4^^^, and in the specimen of P. wombat examined 4^ inches. 



Excepting in the inequality of size, this bone in the first two species 

 is hardly to be distinguished ; but in P. ivombat, although bearing a 

 close resemblance to them in general outline, it has nevertheless 

 pointed differences. Its breadth, both in shaft and extremities, is 

 relatively one-third less ; the deltoid ridge is not so {)rominent ; and, 

 moreover, in P. lAatyrhinus and P. latifrons this has its outer margin 

 rolled backwards so as to give a greater depth behind to that portion 

 of the shaft. The posterior part of the articulating surface of the 

 head of the humerus in the two latter curves considerably backwards, 

 which is not the case in P. wombat, neither has this last such rough 

 processes for the attachment of muscles. In neither of the speci- 

 mens under consideration was the interspace of the condyles perfo- 

 rated*, as is said occasionally to be the case in P. xoombut. 



Ulna and Badius. — These bones in P. platyrhinus and P. lati- 

 frons approach closely to each other, both in the bend of the bones 

 and in the muscular grooves and ridges. 



The separation distinctive between these two species is one only of 

 size ; the ulna of the first, from the olecranon process to the styloid 

 process, is 6", the same measured in the second is 5"'5. The Com- 

 mon Wombat has this bone o"'8 long, but not at all so broad and 

 strong as in them, neither has it such a deep exterior muscular groove, 

 and its sigmoid notch is also relatively smaller in size. 



As to the radius, its length bears an analogous proportion to the 

 other bones of the fore limb — in P. platyrhinus 4"*4, in P. latifrons 

 4"-l, and in P. wombat 4"'2. In the last the shaft is not so strong 

 * Owen, Trans. Zoo). Soc. vol. ii. p. 101. 



