„ , 212 [April 18, 



Cope.] 



Prof. Heinrich Helmholtz, of the University at Berlin. 

 Prof. Theodor Mommsen. 

 Mr. Theodore D. Rand, of Philadelphia. 

 Prof. Joseph LcConte, of California. 

 Prof. John LeConte, of California. 

 Mr. John Fulton, of Saxton, Huntingdon, Co., Pa. 

 Mr. Lloyd P. Smith, of Philadelphia. 

 Prof. Geo. F. Barker, of the University of Pennsylvania, 

 in West Philadelphia. 



And the meeting was adjourned. 



ON THE OSTEOLOGY OF THE EXTINCT TAPIROID 

 HYRACHYUS. 



By Prof. E. D. Cope, A. M. 

 {Bead before the American Philosophical Society, April 18, 1873.) 

 This genus was originally described by Leidy* from portions of skele- 

 tons of individuals from the Eocene tertiary of Wyoming. He recognized 

 it as related to the Lophiodon of Cuvier in dentition, and as sharing with 

 characters of that Eocene genus, peculiarities which belong to the exist- 

 imj genus Tapir us. . 



Having obtained a large series of remains of this genus, including 

 more or less numerous portions of six species with nearly complete 

 skeleton of II. eximim, Leidy, I propose to give such an account of its 

 osteology as will place its relations on a certain basis. 



The characters which distinguish its dentition from those of the allied 



"■enera are as follows : 



Tapirus, Briss. Lower jaw : third molar two-crested ; three premolars, 

 the third and fourth with two transverse crests. Upper jaw: seven 

 molars, first with an inner heel tubercle ; other premolars with two 

 transverse crests. 



Hyrachyus, Leidy. Lower jaw : third molar with two crests ; four pre- 

 molars, third and fourth with one transverse and one longitudinal crest. 

 Upper jaw : seven molars, first without interior heel ; premolars with 

 two transverse crests. 



Lophiodon, Cuvier. Lower jaw : third molar with three cross-crests; 

 premolars three, Nos. 2 and 3 with longitudinal crests. Upper jaw : pre- 

 molars with longitudinal crest only ; No. 4 with two transverse crests. 

 Upper jaw : premolars with only one transverse crest. 



In Hyrachyus the nasal bones are elongate, and unite with the maxil- 

 laries anterior to the orbit ; in H. eximius above the foramen infra-orbitale 

 exterius ; in Tapirus those bones are much shortened, and either do not 



•Hayden'sU. S. Geological Survey of Montana. 1871, p. 361. 



