70 REVISION OF THE PELYCOSAURIA. 



tudinal oval. The maxillary teeth are somewhat weathered and obscured by a thin 

 layer of matrix. The posterior ones are compressed conic ; the premaxillaries are four 

 in number on one side, and are more nearly conic, and have incurved apices. The 

 median premaxillary suture is, however, not clearly defined, so that the number of pre- 

 maxillaries remains uncertain. The center of the probable nostril measures one-third 

 the distance from the premaxillary border to the anterior edge of the orbit. There are 

 eight rows of (?) pterygoid teeth at the posterior fourth of the series. The teeth are 

 subequal and obtuse, increasing a little anteriorly. 



"The mandibular ramus is robust, and the external face slopes inwardly and down- 

 wards. The external border rises a little above a few of the posterior teeth, but it is 

 injured at the posterior of the coronoid process, so that its existence can not be ascer- 

 tained. The border then descends and turns inwards to the articulation, which is 

 condyloid at its internal extremity. The inferior edge of the anterior part of the 

 ramus becomes a median ridge below the condyloid region, and terminates in a short, 

 compressed angular process. The symphysis is not coossified, and is convex down- 

 wards and forwards. The inferior part is subhorizontal, and forms the edge of a 

 transverse plate which is separated from the vertical part of the ramus by a deep 

 groove. The inner vertical face of the ramus is strongly convex, as is the corre- 

 sponding edge of the symphysial suture. The apices of the teeth are worn, but they 

 were probably conic, the posterior gradually smaller and more obtuse. The interior 

 face of packed teeth begins at the posterior two-fifths of the external series, and 

 expands inwards posteriorly. It contains six longitudinal rows opposite the ante- 

 penultimate dentary tooth. 



"All the bony surfaces are smooth. 



Measurements. 



m. 



Length of mandibular ramus (straight) 0.162 Width of extremity of o. quadratum 0.024 



symphysis of ramus (straight) 038 occipital condyle oi8 



external dental series 077 Length of superior dental pavement 065 



Width of ramus at dental pavement 040 Width of basisphenoid posteriorly 029 



skull at ends of 00. quadrata 1 38 



"The supposed axis vertebra is longer than wide, and the centrum is deeply exca- 

 vated posteriorly. Anteriorly it appears to have lost a piece — the centrum of the 

 atlas — which, while fitting it closely, was not coossified with it. There is a flat hori- 

 zontal convex ala in the place of a diapophysis, and an obtuse median hypapophysial 

 angle. The neural spine is compressed, except posteriorly, where it is transversely 

 expanded, terminating above in a short obtusely acuminate apex. From this apex 

 an obtuse rib passes down the median line, and disappears above the neural arch, 

 where the spine is somewhat narrower. The postzygapophyses are well developed 

 and look downward." 



Afeasuremetits of axis. 



m. "t. 



Length of centrum below 0.020 Elevation of spine from postzygapophysis 0.038 



Width, including diapophyses 035 Width of spine, posteriorly 020 



In 1892 Cope gave a short synopsis of the characters of the skull: 



"In Edaphosaiirus Cope, the skull is of a more depressed type than in the pre- 

 ceding genera. The postorbital is mainly preserved, and it is in contact with the 

 frontal (postfrontal) proximally, and sends out no bar posteriorly. There was appar- 



