274 THE PUEKCO FAUNA. 



molars h.ave the structure most like that of the T. heilprinianus, especially 

 anteriorly. The principal anterior cusps are united together for most of 

 their elevation, while the anterior inner is much smaller and lower, and is 

 situated between the middle and inner side of the anterior cusp. The heel 

 is rather wide, and has a raised border. The external part of it is angular, 

 and is somewhat within the vertical line of the base of the crown. The fourth 

 premolar differs from that of the type of the genus, T. quivirensis, in having 

 two acute longitudinal tubercles situated close together on the heel. 



The anterior masseteric ridge is very prominent The masseteric fossa 

 is strongly concave, but shallows gradually inferiorly. Its inferior border 

 presents a low thickened ridge, which is recurved in front. This may be 

 an individual character only. The inferior outline of the ramus is generally 

 convex, and does not rise much below the masseteric fossa. 



Measurements. 



M. 



Length of last four inferior molars 0315 



" " true molars 02:W 



„. ,,. . ( iiiittTonosterior 0065 



Diameters of M. i.S . ,>,,.. 



( t ran verso OOoo 



Length of Pm. iv. on base 0090 



Depth of ramus at M. i O-JOO 



Thickness" " 0065 



This Tritsodon is not only materially smaller than the T. heilprmianus, 

 but differs in the characters of the heel of the inferior molars. In that 

 species the internal border is tubercular; in this one it is entire. The T. 

 conidens and T. quivirensis differ in the arrangement of the anterior cusps. 



Dedicated to my friend, Henry Carvill Lewis, professor of mineralogy 

 and geology in the Academy of Natural Sciences, Philadeli)hia. 



From the Puerco epoch of New Mexico, discovered by D. Baldwin. 



Triisodon conidens Cope. 



Proceedings Academy Natural Sciences, Philadelphia, 1882, p. 297. 

 Plate XXIII d; figa. 9-10. 



A right maxillary bone and corresponding mandibular i-amus represent 

 this species in my collection. The former sustains the last five molars, and 

 the latter the last three, with alveoli of the others and of the canine tooth. 

 The pieces indicate a skull of the size of that of the wolf, and a good deal 

 more robu.st in its vertical measurements. 



