248 Scientific Proceedings^ Ro/jal Dublin Society. 



Ul.NA. 



As is well known, the fore-limb of the Hare is remarkable for showing a 

 specialization of the kind characteristic of the more advanced ungulate types. 

 This is seen most clearly in the form of the distal articulation of the humerus, 

 which has departed far from the primitive type, and in the reduction of the 

 ulna. The latter bone is well on its way to lose, first, the middle, and then 

 tlie lower part of its shaft. Judging from the somewhat scanty recent 

 material before me, the reduction of the ulna is proceeding in a somewhat 

 different direction in L. variabilis from that which it follows in L. europceus. 

 In the latter species the middle part of the shaft of the ulna is rather broad 

 transversely, but is very thin, i.e. greatly reduced, antero-posteriorly. In 

 L. variabilis the converse obtains — the transverse dimension, and not the 

 antero-posterior one, being especially reduced.' 



I have seen no perfect ulna from the Ightham Fissures, although numerous 

 fragments are before me. What remains of the shaft in each case agrees 

 with L. variabilis, and not with L. europceus. Here, as with the other bones 

 from Ightham, the large size is conspicuous. 



Radius. 



The only character that I can mention as distinguishing tlie radius of 

 L. variabilis from that of L. europceus is, that in the former the distal end is 

 proportionally smaller than in the latter, as is evident from the table of 

 measurements. All the fossil radii from Ightham that I have measured agree 

 in this with L. variabilis. They are distinguished from the recent radii and 

 from the fossils described by Woldrich (from Zuzlawitz) and Hescheler from 

 Thaiingen by their very large size. 



1 Newton, Quart. Join: Geol. Soc, vol. Iv., p. 421. 



