326 SYNOPSIS OF THE VERTEBKATE FAUNA OF THE PUERCO SERIES. 



is distinctly lai'ger than the first or the third. The external tubercles of all of the 

 true molars stand within the base of the crown, so that their external faces are unu- 

 sually oblique. They have a crescentic section, and the posterior sends its anterior 

 ridge obliquely to the base of the posterior of the anterior internal cusps, enclos- 

 ing a basin as in Chriacus. There is a delicate cingulum I'ound the base of the 

 crown on all except the internal sides. The first premolar is a robust tooth, with a 

 wide narrow heel, and a small anterior basal tubercle, besides the principal subconic 

 cusp. A delicate extei-nal basal cingulum. The third premolar has a minute heel, 

 and no external or anterior cingulum. Fourth premolar one-rooted. A short space 

 between third and fourth premolars. Enamel minutely rugose, but polished. 



The ramus is not deep, but is robust. Its inferior outline rises posteriorly from 

 below the anterior part of the third true molar. The anterior masseteric ridge is 

 prominent. The coronoid process rises gradually from the third true molar, without 

 cari-ying that tooth with it. The symphysis extends posteriorly to the line of the 

 posterior border of the third premolar. Mental foramina below the second and fourth 

 premolars. 



Measurements. M. • 



Total length of inferior molar series 060 



Length of true molars 030 



f anteroposterior 008 



Diameters p. m. i -,' 



(^ transverse 0065 



^. f anteroposterior 0096 



Diameters m. i < 



(^ transverse 0083 



^. .. f anteroposterior 0105 



Diameters in. n < 



j^ transverse 0098 



... f anteroposterior 0105 



Diameters m.m-^ 



[ transverse 0083 



Depth ramus at p. in. i 019 



" " " m. iii 031 



The seven individuals represented in my collection are all from the Lower 

 Puerco, and the si)ecies is probably confined in its range to that horizon. 



MiOCLiENUS G.\DDIIIANUS Sp. noV. 



In this species we have a form which in various respects suggests approach to 

 Onychodectes. It is represented in my collection by several fragments of the skull 

 of an individual of medium dimensions in the genus. Both maxillary bones are pre- 

 served with most of the molar teeth, and a i)art of the mandible with the last 

 molars. 



The first superior pi-emolar has the principal cusp an acute cone with the section 

 but little compressed. It is joined to an internal cusp whose apex is crescentic. 



