NO. IGSn. THE FOSSIL GENU Si PTILOnUSI—aiDLEY. 615 



aiul -1 of till' k'ft sido. (No. ?m:\ Amor. ]\[us. Nat. Tlist. Coll.) A 

 canine and incisor are represented by their fangs." 



Tijpe-locallty. — Northern New Mexico. 



Ilorhon . — Torre jon format ion. 



The description, as given by Cope, is as follows: 



Char, gen.: These are known from three superior molars; viz; the last pre- 

 molar and tlu! see-onil and third true molars.'' The fourth premolar has two 

 external, and one internal cusps, and the true molars have four cusps each. 

 * * * The second true molar resembles a convex body which has been 

 divided bj' two cuts at right an,irles to each other, from which the (juarters thus 

 produced have spread awaj^ from each other subeyually. The external faces 

 of the cusps are convex. 



^Icasiircinciits (after Cope). 



M. 



Diameters of I'.-m. iv [pmij^j ••■'--"» — .-"- .0080 



.0038 



_. .0033 



.0035 



ior . 0035 



.00.30 



Diameters of ni. ii 

 Diameters of m. iii [imi^J 



, n f antiToposterior 

 IV Lpmi]_J * 



I transverse 



IpjjjL.j janteroposterior 



1 tra 1 IS verse 



Janteroposter 



1 transverse 



The description of the Neotype, as given by Cope, is as follows: 



This jieuus was described by the writer in 1883, from a few teeth of the 

 upper jaw found in the Puerco [Torrcjon] formation of New Mexico. Since 

 then a palate with the entire molar series of one side and nearly all that of the 

 oilier has been obtained. This shows that the teeth described are premolars, 

 and that there are two true molars, which resemble those of Polymastodon and 

 Neoplayiaulax. The premolars are a good deal like those of Plagiaulax, as 

 described to me by I'rofessor Osl)orn, and the question arises whether the denti- 

 tion in (piesticm does not belong to Ptilodus. There are two reasons for answer- 

 ing this question in the negative. First, in I'lagiaulax and Neoplagiaulax, 

 according to Osborn and liemoine, there is a tooth in the superior series re- 

 sembling and opposing the peculiar-cutting fourth premolar of the inferior 

 series; second, the only tooth which could oppose such an inferior premolai" is 

 the first molar, and this is not worn obliquely, as hi Plagiaulacidte, but trans- 

 versely, as in Polymastodon. This and the second true molar support two and 

 parts of a third longitudinal rows of cusps, which are, on tlie last tooth, worn 

 by anteroposterior movement of an inferior tooth of corresponding form. 



As previously mentioned, the genus CJnfox is now known to have 

 been fomided on the upper dentition of Ptiloihis. The species, how- 

 ever, is probably distinct from P. medicprus^ apparently representing 

 a larger form. 



PTILODUS MONTANUS Douglass. 



Ptilodus montanus Douglass, Annals of the Carnegie Museum, V, No. 1, 

 October, 1908, pp. 11 to 20, pis. x and xi. 



Type-specimen. — A portion of the left lower jaw, containing the 

 first molar and the last premolar. (No. 1673, Carnegie Museum Cata- 

 logue of Vertebrate Fossils.) 



« Cope, Amer. Naturalist, XXI, 1887, p. 566. 



^ These are all premolars, as afterwards recognized by Cope. 



