162 THE MAMMALIA OF THE DEEP EIVER BEDS. 



of the head of the metatarsal is in contact with the ectocuneiform element of the 

 compound bone. The shaft has considerable dorso-plantar diameter, but is very 

 much compressed laterally, and therefore, when seen from the front, appears to be 

 exceedingly slender. The third metatarsal is considerably longer than the second, 

 though relatively very much shorter than in the other genera of the family, and is 

 very massive. The proximal facet is almost plane and articulates only with the 

 ectocuneiform ; a process on the fibular side slightly overlaps mt. iv, but appears not 

 to reach the cuboid ; if it does, the contact is very slight. The fourth metatarsal is 

 somewhat longer and rather heavier than the third, and by its broad, plane proximal 

 surface occupies nearly the entire distal side of the cuboid. The fifth metatarsal is 

 somewhat longer and not so compressed and slender as the second ; its contact with 

 the cuboid is small and rather lateral than distal. 



The phalanges do not differ in any important respect from those of the manus ; 

 they are somewhat longer and narrower, and those of the lateral digits are smaller. 

 In particular, the unguals of these digits are very small. 



CYCLOPID1US Cope. 



Proceedings Amer. Philos. Soc, Vol. XVII, p. 221. 



The distinction of this genus from Leptauclienia is an obscure one. Cope defines 

 Cyclopidius in brief as being " Leptauclienia without superior incisor teeth;" but 

 this character appears not to be altogether constant, for some specimens show a small 

 alveolus in each premaxillary, and others, described below, have two minute upper 

 incisors on each side. All the peculiarities of Leptauclienia are exaggerated in this 

 genus. The lower incisors are reduced to two in each ramus. The upper canine is 

 usually very small and extends but little below the level of the premolars; the latter, 

 especially the two anterior ones ( p.i and M), are, in the typical species, reduced in 

 size and simplified, but none are lost. The molars are more prismatic than in Lep- 

 tauclienia, and in the upper series the external pillars or styles are more prominent. 

 The first lower premolar retains the form and function of the canine, but is only 

 slightly larger than in the canine proper. The facial region of the skull is much 

 shortened and the vacuities enlarged ; the brain-case is small and narrow, but the 

 great expansion of the roots of the zygomatic processes makes the cranial region 

 very broad and low. The auditory meatus is very long and its opening has a more 

 elevated position than in Leptauclienia. The frontal zone is very short and the 

 front als form but little of the cranial roof. The nasals are short and slender rods, 

 expanding somewhat anteriorly, where they meet the ascending processes of the 

 maxillaries and premaxillaries ; the latter are very small. 



