PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. 13 



all. They are all conical, slender, and more or less recurved. At the posterior 

 end of the maxillae there are a few that reach a length of only 4 mm. From this 

 point they increase rapidly in length to an average of about 1 1 mm. At the base 

 the cross-section of all is probably 3.5 mm. or less. 



The septomaxillcB are small, triangular elements, fully twice as long as wide, 

 and form nearly the entire posterior border of the nares. They extend back be- 

 tween the nasals and the maxillae, but are apparently separated from the lachrymals 

 by a considerable space. The nasals are large, rectangular in shape, about three 

 times as long as wide. While the lateral boundary is not certain, the anterior 

 half seems to be formed by the maxillae and the posterior half by the lachrymals. 

 Anteriorly, the nasals take part slightly in the inner posterior border of the nares, 

 posteriorly they have a broad connection with the frontals and connect slightly; 

 perhaps, with the prefrontals. 



The frontals are long and narrow, being fully four times as long as wide. They 

 extend nearly to the posterior border of the orbits. The anterior three-fifths of 

 the lateral boundary is formed by the prefrontals and the postero-lateral border 

 seems to be formed by the post-frontals. Lying about 25 mm. or 30 mm. behind 

 the nares and between the nasals and the maxillae there seems to be a long, narrow 

 element, the lachrymal. To all appearances it takes part in neither the border of 

 the nares nor that of the orbit. The posterior boundary is formed by the pre- 

 frontals and the maxillae. The prefrontal is a triangular bone forming the entire 

 anterior border of the orbit. Anteriorly it connects slightly with the nasals. The 

 postfrontal forms the upper border of the orbit and apparently excludes the frontal 

 from that opening by uniting with the prefrontal anteriorly. It extends back of 

 the posterior border of the orbit some distance between the parietal and the post- 

 orbital. While the suture on the inner side is not certain the element seems to 

 have but little lateral extent. The parietal is sub-rectangular, long and narrow. 

 The posterior extremity is missing and its full extent can not be determined. 

 Laterally it is bordered from the front backward by the postfrontal, postorbital, 

 and supratemporal. 



The postorbital is rather large, as wide as long, and forms the entire posterior 

 border of the orbit. Immediately behind this and in contact with the parietal 

 above lies a large rectangular element, probably the supratemporal. Bounding 

 this below is a small portion of the squamosal, the lateral extent of which can not 

 be determined, as the lower part is missing. At best, however, it must have been 

 a comparatively small element. A small rounded notch, apparently the ear notch, 

 separates the supratemporal and the squamosal for a short distance posteriorly. 

 The jugal is a large element extending from the anterior border of the orbit back 

 at least as far as the ear opening. It forms the lower posterior border of the orbit 

 and increases somewhat in width posteriorly. 



Unfortunately a complete knowledge of the region of the ear opening is pro- 

 hibited by the condition of the specimen. When found the skull was broken through 

 at this point and some of the bone was weathered from the exposed surfaces. The 

 quadrate is present in the matrix, however, and serves to give some idea, at least, 

 of this part of the skull. From the upper side of the quadrate a thin, plate-like 

 bone extends up and forward in a direction as if to connect with the skull just 

 above the ear notch. The outer edge is rough and pitted like the surface of the 

 skull, while the posterior, incurved surface is smooth. The position of this process 

 is such as to suggest its homology with the downward exten.sion of the tabulare 

 in Cacops Williston.* In that genus the tabulare extends back and downward to 



• Williston, Bull. Geol. Soc. Am., vol. 21, p. 354. 



