G. NATURAL HISTORY AND ZOOLOGY. 337 



parts in question, the material for which he found chiefly in 

 the British Museum, and in several collections at Puy, France. 

 He thus found that in the Artiodactyls, numerous as they are 

 in families and species, the similarity is so great that, notwith- 

 standing the diversity which prevails in size and the modifi- 

 cations of other parts, and even of the feet, " we may trace 

 throughout the whole, not only the number and shape of 

 their carpal and tarsal bones, but even each separate facet 

 of these bones, and jDoint it out as clearly in the reduced limb 

 of a land antelope as it is displayed in the complete unre- 

 duced limb of the aquatic hipj)opotamus;" and this similarity, 

 says Dr. Kowalevsky, is so great that " we can not explain it 

 in any other way than by community of descent." The prin- 

 cipal modifications in those parts are exhibited, in the progress 

 of reduction of the digits, by the diminution and final disap- 

 pearance of the trapezium, and the confluence at an early age 

 of the trapezoid and magnum in the carpus, while the com- 

 mon likeness of the bones of the tarsus is still more striking, 

 and the modifications are chiefly in the size of the marginal 

 bones and the coalescence or non-coalescence of cuneiforms. 

 The metacarpals and metatarsals exhibit interesting rela- 

 tions, and adaptive and non-adaptive modifications. 



The forms embraced under the common name Hyopota- 

 mida3 and Anthracotheriidre had been considered to be most 

 nearly allied to the hogs and related forms; but the investiga- 

 tions of Dr. Kowalevsky conclusively prove that such is not 

 the case, but that they were true ruminants, and, according 

 to Professor Gill, their allies are quite numerous in this coun- 

 try, and are found in the genera and species combined un- 

 der the family name Oreodontida?, the remains of which are 

 so abundant in the miocene and pliocene deposits of the 

 West. The Hyopotamidas as well as the Oreodontidae have 

 the canines modified like the incisors, as in ordinary rumi- 

 nants, and the molar teeth have also the usual crescenti- 

 form folds, but they differ in the produced snout and the 

 dentition, and especially the modifications of the premolars. 

 The earliest known representatives of the family have been 

 found in eocene deposits, and during the eocene and mio- 

 cene epochs they were the most abundant and character- 

 istic of ungulate mammals. They did not survive the lat- 

 ter epoch, and have left no successors. In size they ranged 



