678 THE BEIDGEE FAUNA. 



TRIPLOPODID^. 



Cope, American Naturalist, 1881, April (March 25), p. 340. 



But one genus of tliis family is known at present, but the number will 

 probably be increased when the structure of the feet of various imperfectly 

 known species is ascertained. 



TRIPLOPUS Cope. 



American Naturalist, 1880, p. 383 (April 27.) 



14 3 



Dental formula, I. 1; C. -; Pm. ; -; M. ^; a considerable diastema 



1 4 3 



anterior to tlie first premolar. Molars with only two vertical external 

 ridges, viz: the anterior cingular and the approximated median of the an- 

 terior crescent. Transverse crests two, uninterrupted and rather oblique ; a 

 ? third and short crest on the posterior base of the first true molar. Premo- 

 lars different from molars, the third and fourth with two transverse crests. 

 Inferior molars with two transverse crests, as in Lophiodon, the last without 

 heel. 



An ossified inferior wall of the meatus auditorius externus. Posttym- 

 panic and paroccipital processes distinct from each other. No postorbital 

 arch. Postparietal and mastoid foramina preserved ; the latter large. 

 Cervical vertebrae rather long; axis with subcylindric odontoid process. 

 Scapula with small coronoid process. Great tuberosity of humerus long, 

 curved. No trochlear crest on condyles of humerus ; epicondyles rudi- 

 mental. Ulna and radius distinct throughout their length ; ulnar articula- 

 tion with carpus, small. Trapezoid bone of carpus with a facet for the 

 trapezium. Unciform with two inferior facets. Metacarpals three principal 

 ones, and one, the fifth, rudimental ; the distal extremities of the second 

 and fifth opposite ; the third a little longer. 



The dentition of this genus is nearly that of Hyracliyus. The only 

 exception is the possible third transverse crest of the first true molars.^ The 

 other portions of the skeleton known are also much like those of Hyrachyus, 

 with the exception of the number of digits of the anterior foot. The en- 



' This point is farther considered in the description of the species. 



