484 DESCRIPTION OF A NEW GENUS AND NEW SPECIES 



Order BELLUiE L. (Pachydermata, C.) 



Family Proboscidia. 



Genus Tetracmdodon.* (Godman.) 

 Dental Formula: Incisive f, Canine %%, Molar ff, = 12. 

 Character: having four tusks; of which two, large and 

 strong, similar to those of the Mastodon, helong to the upper 

 jaw, and two, small, short and spiral, project from sockets on 

 each side of the chin. The lower jaw produced or elongated 

 at the symphisis; having on its superior surface a smooth 

 hollow groove for the tongue, and terminating in a narrow 

 apex containing sockets for the inferior tusks. 



Species 1. T. Mastodontoideum. Godm. 



In addition to the preceding details, the species will he suf- 

 ficiently characterized by observing, that in the lower jaw of 

 the adult its outlines are peculiarly straight or rectangular, 

 exhibiting none of those bold curvatures and projections so 

 conspicuous in the allied genus Mastodon, about the angles 

 and base of the jaw. The condyloid process is thrown far- 

 ther backward, and the coronoid process is not separated from 

 it by a deep semilunar notch, as in the other genus, the bone 

 gently ascending from the tip of the coronoid until it terminates 

 in the condyle. These peculiarities clearly indicate a very 

 marked difference in the arrangement and power of the mus- 

 cular apparatus, as well as suggest thoughts of differences in 

 mode of life and regimen, between the two genera during 

 their existence. 



Of this highly interesting species, we are now aware of the 

 preservation of fragments of three well authenticated indivi- 

 duals. Two adult jaw bones (one of which is nearly two- 

 thirds entire) in the Museum of the University of Virginia ; 

 the young specimen, the immediate subject of this descrip- 



* From Tirga, four; and ^vKUiavra., tusks. 



