26 



of these bones are quite diiferent from what exists in that genus, and is 

 rather that of the Camelidce and other ruminants, or what Kowalevsky 

 has called the " adaptive type." This author has seen in the genus Gelocus, 

 Aym., from the lowest Miocene or upper Eocene of France, the oldest rumi- 

 nant, and the probable ancestor of a number of the types of the order, 

 but among these he does not include the Camelidce. The present genus 

 as a more generalized type than Geloous, in its separate trapezoid and dis- 

 tinct metacarpals rei)resents an early stage in the developmental his- 

 tory of that genus. It also presents affinity to an earlier type than the 

 TraguUdw, whicli sometimes have the divided metacarpals, but the trap- 

 ezoides and magnum co-ossified. In fact Poebr other iuni as direct ances- 

 tor of the camels, indicates that the existing Buminantia were derived 

 from these lines represented by the genera Gelocus for the typical 

 forms, Foebrothernim for the camels, and Hyaemoschus for the Traguli- 

 dcB. The first of these genera cannot have been derived from the sec- 

 ond on account of the cameloid cervical vertebrae of the latter, and all 

 three must be traced to the source whence were derived also the Anoplo- 

 theriidce, perhaps the little known Dichodontidce. 



The two distinct metacarpals, separate trapezium and trapezoides, 

 cameloid cervical vertebrte and dentition, characterize this type as a pe- 

 culiar family which may be called Foebrotheriidce. The genus from 

 which it takes its name was originally referred by Leidy to the Camelidce. 

 Allied genera are Hypertragulus Cope, Leptomeryx Leidy, and Hypisodus 

 Cope, but there is good reason to believe that most or all of these 

 genera are true ruminants, having the two metacarpals co-ossifled, and 

 the cuboid and navicular bones more or less completely united. Their 

 cutting premolar teeth and foot structure refer them to the Tragulidce, 

 if the cervical vertebrae are not cameloid. 



Hypisodus minimus Cope ; Lepiauchejiia minima Cope, Pal. Bulletin, 

 No. 16, p. 8 ; Hypisodus ringens Cope, Synopsis New Vertebrata, Colo- 

 rado, p. 7. 



This exceedingly small ruminant was very abundant during the pe- 

 riod of the Oreodons, &c. I cannot discover any characters in the 

 portions of dentition, (all except the superior P. M. 1 aud 2,) at my dis- 

 posal, by which to distinguish it from Poebr otherium, although such may 

 exist. The incisors, canine, and first premolar form an uninterrupted 

 series of ten simple teeth at the symphysis. 



This genus should doubtless be referred to the same group as Lep- 

 tomeryx, Hypertragulus, etc. 



Hypertragulus oalcaeatus Cope, gen. nov. Leptauchenia calcarata 



Cope, Pal. Bulletin, No. 16, p. 7. 



This genus is allied to Dremotherium Geoffr., and Leptomeryx Leidy. 

 The diagnoses may be thus compared ; that of the first I derive from 

 Pomel. 



Hypertragulus Cope. Molars 6-6 ; first superior jjremolar without in- 

 ternal lobe ; inferior premolars differing in form, the first one lobed, 

 situated at a distance from the second, which is sectorial and not three- 

 lobed. 



Dremotherium Geoff. Molars 6-6 ; first superior premolar without in- 

 terior lobe; inferior premolars similar, three-lobed and contiguous. 



Leptomeryx Leidy. Molars 6-6 ; first and second superior premolars 

 three-lobed, and with an internal lobe, third with an inner and an outer 

 crescent. Inferior premolars similar, three-lobed and contiguous. 



In Hypertragulus the third upper premolar exhibits an internal as well 



