12 PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. 



The skull is long and narrow, broadly rounded anteriorly, with the sides 

 diverging slightly and regularly in the anterior four-fifths of the length. From 

 this point the outline is slightly convergent. The greatest length of the specimen 

 is about 288 mm. The width at a point 30 mm. back of the tip of the rostrum, 

 the approximate length of the radius of the rounded anterior border, is about 

 54 mm. The greatest width of the skull was probably not over 90 mm. The 

 sides rise abruptly to the plane of the table of the skull. In a lateral view the 

 profile is triangular and low (fig. 4 a). The upper border of the anterior half is 

 nearly straight and rises gradually from a height of about 13 mm. near the tip to 

 about 33 mm. near the middle. From this point it rounds up gently in a concavo- 

 convex curve to the horizontal plane extending over the posterior third of the 

 skull. The greatest height is approximately 65 mm. 



The orbit is nearly round and is about 32 mm. in diameter. The anterior 

 border is a little back of the middle of the skull. The plane of the orbit is parallel 

 with the lateral margin of the skull and is directed out and slightly upward. No 

 sclerotic plates are present. The naris, which has a rounded anterior border and 

 is straight behind, is about 10 mm. wide and 7 mm. long. It is placed near the 

 lateral margin of the skull, about 50 mm. behind the tip of the rostrum. Its plane 

 is directed out and upward. No pineal foramen has been observed. It is possible, 

 however, that one was present, but slightly to the right of what seems to be the 

 median line, and that it has been broken away in this specimen. From the middle 

 of the posterior border of the orbit a depression extends back and slightly down for 

 a short distance. A similar depression extends forward from the anterior border 

 of the orbit and a third, somewhat smaller, lies a little behind the naris and in a 

 line with the orbit and the naris. The dorsal surface (fig. 4 b) of the rostrum is 

 slightly concave laterally from a point near the tip back nearly to the middle of 

 the skull. The entire surface of the skull is marked with irregular pitting. In the 

 upper posterior portion the pits are large and deep and are separated by irregular 

 ridges. Anteriorly and below the pits become progressively smaller. Occasion- 

 ally they run into each other to form antero-posterior grooves. This is especially 

 true on the posterior end of the jugal. Here several lie parallel and are crowded 

 close together. Extending back from the lower posterior comer of each naris is a 

 smooth, shallow groove, evidently a mucus canal. The specimen probably belongs 

 to an adult individual, for the ossification is so complete that no trace of suture 

 is seen between the parietals or the frontals. 



The premaxillcB are large and broad. They form the lateral boundaries of 

 the nares as well as their anterior border. Their posterior border forms a con- 

 cavity into which the nasals extend. The sutures bounding the maxilla are uncer- 

 tain, except for a short distance near the anterior end. From the narrow anterior 

 extremity, which enters but slightly into the posterior border of the nares, they 

 gradually broaden posteriorly to within a short distance of the orbit. From here 

 they rapidly narrow to the posterior end, which apparently takes part slightly in 

 the lower anterior border of the orbit. The extremity seems to be extended into 

 an upper and a lower process that embrace the jugal. The teeth extend back to 

 the middle of the orbit. Many of the teeth of the premaxillse and the maxills are 

 broken or wanting; still a fairly good idea of their size and number can be gained 

 from those present; they are placed rather irregularly and show some variation 

 in size. Apparently there is no arrangement according to size except that the pos- 

 terior ones are all small. The variation in length and diameter is due, perhaps, 

 to new teeth taking the place of those that have been lost. On each premaxilla 

 there are 8 or more teeth and on each maxilla about 18, or between 52 and 56 in 



