308 SYNOPSIS OF THE VERTEBRATE FAUNA OF THE PUERCO SERIES. 



inferior incisor. The latter issues from the jaw at a considerable distance in advance 

 of the first premolar, leaving a wide diastema, which has a rather wide and obtuse 

 superior surface. The alveoli of the true molar are within the base of the coronoid 

 process, and indicate a tooth of much smaller size than the premolar. The symphysis 

 is short, and is indicated almost exclusively by rugosities of the inferior and anterior 

 border of the extremity of the ramus. The articulation has been a loose one by 

 ligament. 



MeasuremcnU. M. 



Length of fragment of ramus 057 



" " diastema 013 



anteroposterior 013 



Diameters p. ni. i , . , „„_ 



transverse posteriorly 005 



Length of base of m. i (estimated) 006 



Depth ramus at diastema , 016 



" << «' posterior base of p. m. i 031 



( vertical 007 



Diameters of incisor I 



> transverse 004 



The tooth from which the species was originally characterized has the following 

 characters : Length of base one-third greater than in Neoplagiaulax americanus, and 

 there are fifteen keel-crests on the side of the crown, while there are but seven in the 

 N. mnericanus. The outline of the crown is elongate and moderately convex, and 

 less elevated than in the known species of Ptilodus. The irregularity in the outline 

 of the base of the crown is less than in the other species, and the diameter of the 

 roots is subequal. The anterior base of the crown is not excavated for the second 

 premolar as in Ptilodus. Length of base of crown, 16 mm. ; elevation at mid- 

 dle, 8 mm. 



In size this species is about equal to the P oly mastodon foUatus. 



CREODONTA. 



Important additions to the knowledge of this suborder have been made recently 

 by Professor W. B. Scott* and Dr. Max Schlosser.f The former has determined the 

 presence of the siibcylindric postzygapophyses in Didymictis, and I have ascertained 

 their existence in Esthonyx and Dissacus. Scott shows that in HyjTJuodon the char- 

 acters of the carpus and of the brain coincide with those of this group. He also 

 finds an os centrale in that genus and in Mesonyx, and Osborn has found it in 

 Esthonyx. 



In the following pages considerable additions to the general osteology of Hemi- 



* On Some New and Little known Creodonta ; Jour. Acad. Phil., 1880, p. 15.5. 



\ Die Affen, Lemuren, Chiroplcrcn, Insectivoren, Marsujiialia, Crcodouten und Caniivoren des Europiiischen Ter- 

 tiars ; Wien, 1887. Alfred Holder. 



