418 WEALDEN BIED AND MAMMAL. [^Ug- 1 899, 



lophodon,^ in which the external side of the hone is deeper and 

 produced distally in the condyle, there is practically a flat external 

 surface to the bone and no inferior development to the condyles. 



The character of the fossil which, in view of its partial approxi- 

 mation to Colymbus, might be regarded as least avian, is the deep 

 notch between the condyles on the inferior surface, and this some- 

 what Iguanodont character is replaced in Hypsilopliodon by a broad 

 open notch which is much more bird-like. Some of the Crocodilia 

 closely approach this femur in the form of the distal end. There 

 are many points of resemblance in Crocodilus Spenceri^ especially in 

 the distal prolongation of the condyle, and the same character is 

 seen in Crocodilus sivalensis. But in no known crocodiles, recent or 

 fossil, are the inferior condylar surfaces so much developed. The 

 femur of Heterosuchus is not known : but it is probably the only 

 crocodile which might so approach this type of animal as to suggest 

 caution in unqualified acceptance of its avian interpretation. 



Discussion on the two eoeegoing Papers. 



Mr. E. T. Newton agreed with the Author as to the mammalian 

 affinities of the humerus from near Tonbridge, but thought that 

 the bone had been much denuded, and that its form indicated a 

 late Tertiary or even more modern origin. The characters of the 

 fragment of a femur from near Cuckfield seemed to him to point 

 rather to crocodilian than avian affinities. 



Mr, R. Ltdekker and Mr. C. W. Andeews also spoke. 



The AuTflOE said, with reference to the suggestion that the 

 mammalian fossil was of Tertiary age, that no generic type had 

 been suggested for comparison. He was able to state, after com- 

 pairison of the specimen with materials in the British Museum, that 

 there is no fossil to which it approximates sufficiently to necessitate 

 detailed comparison. No such fossil, so far as he was aware, had 

 ever been figured. The resemblances are probably closer with 

 living than with extinct genera, though the fossil is in some 

 respects more generalized than either. 



With regard to the suggestion that the lower borders of the 

 olecranon-pit are worn, he drew attention to the fact that the 

 character is only an intensification of a feature common in the 

 same position in the humerus in antelopes and deer, though not 

 limited to those groups. There is in the dry skeleton an ovate 

 vacuity between the hinder distal end of the humerus and the 

 olecranon-process of the ulna, which varies in size in different 

 genera : in this fossil it appears to have been unusually large. 

 The surface in question on this humerus shows no sign of wear, for 

 it is concave, and corresponds with the recent specimens in con- 

 dition. He had nothing to add concerning the Cuckfield bone, as 

 the views which had been suggested are stated in the paper. 



^ Hulke, Phil. Trans. Eoy. See. vol. clxxiii (1882) pi. Ixxviii. 



