148 



Dr. W. Kowalevsky on the 



[Feb. 6, 



and specific forms, I deem to be of great importance in our speculations 

 on the pedigree of living Ungulata Paridigitata. 



On theoretical grounds, as well as from the consideration of rudimental 

 parts hi living Paridigitata, anatomists have always supposed that fossil 

 representatives of this family, which could be regarded as the progenitors 

 of the recent Paridigitata, would certainly exhibit a much less reduced 

 skeleton and a more complete number of digits than the recent genera 

 do. Yet, strange to say, such complete forms were not forthcoming, 

 and, i£ assumed on the evidence of their teeth, very little was known about 

 the structure of their bony frame. My statement will sound like an 

 exaggeration; but still it is true, that since the time of Cuvier, who 

 shortly noticed the tetradactyle Dichobune, and Blainville, who gave a very 

 imperfect description of Cainotherium, we have absolutely not a single 

 paper in which the osteology of an extinct genus of Paridigitata has been 

 fully given *. This may partly be the reason that the pedigree of living 

 genera has hitherto been so obscure. 



The Paridigitata of the Paris gypsum, described in a masterly way by 

 Cuvier (the Anoploiherium and Xiphodon), were clearly extremely reduced 

 descendants of some earlier more complete forms ; their feet presented, 

 in fact, nearly the same degree of reduction which we find hi our recent 

 Puininantia, save the confluence in a cannonbone. Seeing the reduced 

 state of their skeleton, how could they be taken as progenitors of the very 

 rich family of Ruminants, some of which have retained, even till our 

 times, a tetradactyle limb ? However, so great was the want of some 

 form from which the living Riunhiantia could be assumed to be derived, 

 that nearly all comparative anatomists and palaeontologists who speculated 

 on these questions of descent, placed the Anoploiherium and Xiphodon 

 at the head of the series, as the fons et origo wheref rom all living Bumi- 

 nantia have descended. 



The present paper is an attempt to introduce to palaeontologists a new 

 form, which, though known by its dental system more than twenty-five 

 years ago. has remained totally unknown, so far as its skeleton is con- 

 cerned. This skeleton, by its completeness, has proved to be a very inter- 

 esting one, not only in a concrete way, but as furnishing a clue to the 

 understanding of the skeletons of those forms which, though totally un- 

 known, must have preceded Anoploiherium and Xiphodon in time, and from 

 which these two may have descended. 



Besides, the greater importance of the Ryopotamidce in comparison with 

 Anoploiherium and Xiphodon lies in the fact, that, while these two last 

 were but poorly differentiated, presenting only two or three distinct spe- 

 cific forms, the Hyopotamidce, on the contrary, strike us by the extreme 

 diversity and richness of their specific and generic forms. Beginning 



* No doubt we have excellent memoirs, like the works of Gaudry, Kutimeyer, Fraas, 

 and H. v. Meyer ; but the Paridigitata described in all these do not materially differ 

 from those now living, at least so far as the skeleton is concerned. 



