222 



The maxillary preserved is nearly perfect, and may belong to another 

 animal ; its depth coincides with that of the premaxillary. It is quite elon- 

 gate ; about nine times as long as deep ; perhaps a little more. It supports 

 forty-two closely-packed teeth, not all in functional service at once. The 

 distal end is contracted and grooved, and ridged on the inner face, as though 

 for union with a supernumerary bone. The external face is longitudinally 

 striate on the posterior half; the stria? running out to the margins, forming 

 sharp rugosities on the alveolar border. The superior (f palatine) articular 

 surface is more than one-fourth the total length from the anterior extremity ; 

 it is narrow, and somewhat lens-shaped. Both behind and in front of it, 

 strong striae run from the outer to the inner side of the superior margin sub- 

 longitudinally. Posterior to the superior articular surface on the outer face 

 is a swelling like a muscular impression, from which grooves and keel extend 

 posteriorly. The bone is concave on the outer face in front, to accommodate 

 the os premaxillare. 



The mandibular rami are abruptly incurved at the symphysis, which is 

 not serrate, and is subround, with an emargination entering from the inner infe- 

 rior side. The dentary bone is much narrowed behind. The angular bone 

 extends anteriorly on the inner face to the end of the posterior two-fifths of 

 the dental line. The ramus is not very deep at the coronoid region. The 

 articular cotylus is composed more largely of the angular than the articular. 

 Its long diameter extends inward and backward, and is strongly convex; in 

 the transverse direction, slightly concave. Below and in front of it, the lower 

 margin of the jaw is acute. The angle is oval and rather small ; it is promi- 

 nent on the middle line on the inner side ; the edges are thin, the upper 

 curved outward, concealing part of the cotylus. There are twenty-nine teeth 

 on the dentary, whose sizes diminish toward its extremities. Their roots 

 arc very large and longitudinally striate and porous. Opposite the interval 

 between the first two teeth, there is a tooth exterior to the general row, and 

 another on its inner side. They are not enlargrd. 



No teeth are preserved except on the maxillary. These arc not very 

 elongate cones, with round section, and well curved inward. Dense external 

 layer entirely smooth. 



This species differs from the type P. basalts, Dixon, in that the radical 

 portion of the tooth is less swollen and more conic, and docs not project 

 above the exterior alveolar wall, as in that fish. 



