MORPHOLOGICAL REVISION OF THE SUBORDER. 91 



The end of the muzzle was abruptly rounded and high with the nostrils lateral, 

 but quite near the anterior edge. The tooth line of the maxillary is convex and there 

 is a slight diastema! notch between the maxillary and premaxillary. This is really 

 less well-developed than appears in the figure, where it is accentuated by the crushing 

 of the specimen ; it is most clearly indicated by the size of the teeth. The teeth are 

 similar to those of Dinietrodoii; as in that genus there were two large maxillary 

 canine teeth which were alternately functional, for in each maxillary there is a large 

 tooth and an empty alveolus. On the right side there are fifteen teeth posterior to 

 the large canines, two canines, or rather one and an empty alveolus, and three or four 

 teeth preceding the canine, making twenty or twentj^-one in all. On the left side the 

 teeth are less perfectly preserved. The canine is abruptly larger than the others with 

 an elliptical section and sharp anterior and posterior cutting edges, but the edges are 

 not crenate. Posterior to the canine the teeth are gradually reduced in size until 

 the posterior ones are very small. There were four teeth in the premaxillary; the 

 anterior three are larger than the posterior ones, but are not nearly so large as the 

 maxillary teeth immediately following the canine. 



The posterior portion of the skull is badly crushed and only a few points can be 

 made out with certainty. They show that the previous description of this portion of 

 the skull by the writer was correct (29). On both sides of the skull the outline of 

 the anterior portion of the orbit can be traced and shows that it was large, nearly cir- 

 cular, and surrounded by a prominent rim as in Dimetrodon. A jugal can be traced 

 below. On the left side the fractured postorbital region shows the jugal connecting 

 with the prosquamosal (?) posteriorly and with the postorbital above, which though 

 broken and displaced can still be traced. The edges of a large inferior temporal vacuity 

 are distinct and the superior temporal vacuity was small. It is certain that the animal 

 had a diaptosaurian skull closely similar to, but more primitive than Dimetrodon. 



The lozver jazv is very similar to that of Dimetrodon iiicisiviis in form and pro- 

 portions, but the sutures can not be traced. The ramus was more slender and with a 

 longer symphysis in which the splenial takes large part. The posterior end is widened 

 and there is no coronoid process. The articular region is hidden. The teeth are 

 mostly hidden so the number can not be given, but on the left side there were three 

 large teeth at the end without a smaller one preceding them, as is common in the 

 genus Dimetrodon. The alveolar edge of the dentary is concave to correspond to the 

 convex edge of the maxillary. 



The vertebral column : No vertebrse from the anterior portion of the column 

 have been identified. The dorsals are represented by several loose vertebrje from the 

 postdorsal region ; three connected vertebrse with ribs show the chief characters. The 

 centra are relatively elongate with the base of the spine elongate antero-posteriorly and 

 set well back over the posterior zygapophyses ; the faces of the zygapophyses are nearly 

 horizontal. The transverse processes are very slender and stand out straight from the 

 neural arch. The ribs are large and two-headed with a strong tuberculum and the 

 shaft nearly straight. 



An anterior lumbar has the centrum and neural arch elongate antero-posteriorly; 

 the transverse process is slender and the lower supporting ridge runs forward to the 

 anterior edge of the centrum and joins the face for the capitulum of the rib. 



Of the five vertebrse in connection with the pelvis and sacrum t\\e.Jirst two have 

 the centra still rather long; the bottom line is thinner and rounded, but not keeled. 

 The base of the neural spine is thin, but wide antero-posteriorly. The ribs are firmly 



