84 THE MAMMALIA OF THE DEEP KIVEK BEDS. 



DESMATIPPUS Scott. 



Amer. Naturalist, 1893, p. 661. 



Equities in which the dentition is intermediate in character between that of 

 Mioliippus and that of Protoliippus. The molars and premolars are short crowned 

 and have the valleys more or less filled with a thin deposit of cement. In the upper 

 series, the posterior transverse crest is connected with the outer wall, and in the mid- 

 dle of its course sends forward a process which extends nearly to the anterior conule. 

 The posterior pillar is enlarged, and on moderate wear becomes confluent with the 

 postero-internal cusp. In the lower cheek-teeth the internal cusps are reflected and 

 expanded antero-posteriorly, so as to narrow the entrances to the valleys. The 

 median inner cusps (a a 1 of Eiitimeyer) are much more distinctly separated than in 

 jinchitJierium or Mioliippus. 



Desmatippus crenidens Scott. 



(PL II, Pigs. 9-14.) 

 {loo. cit.) 



Size moderate; limbs elongate and slender; posterior transverse crests of upper 

 cheek teeth crenulate. 



This interesting genus fills very completely and satisfactorily what was almost 

 the only gap left in the equine phylum, viz., that between Mioliippus and Protoliip- 

 pus. At first sight it might seem to be identical with the Merychippus of Leidy, 

 but this genus was established upon two upper milk molars (No. 23, PI. XVII, 

 Figs. 3 and 4) of peculiar construction, the reference of which is still entirely uncer- 

 tain. The permanent dentition which Leidy has referred to this genus differs alto- 

 gether from that of Desmatippus, being much more like that of Protoliippus, with 

 which Cope identifies it. 



The type specimen of the new genus consists of the dentition of both jaws, 

 lacking the incisors, canines, first lower premolar and last upper molar, the mandible, 

 portions of the radius and ulna, femur, manus and pes, and fragments of other bones. 

 Other specimens, which should probably be referred to the same genus, though per- 

 haps a different species, will be described in the sequel. 



Dentition. A. Upper Jaw. The first premolar, though much smaller than the 

 others, is relatively large and well developed, and is composed of four elements. The 

 protocone, which is much the largest, is elongate, somewhat convex upon the outer 

 face and displays a rounded projection upon its inner face. The tritocone is small, 

 not very distinctly separated from the protocone, and is overlapped by the greatly 

 extended anterior buttress or protostyle of Ei^. The deuterocone is represented by a 



