42 AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



crescent with subacute horns, which terminate below the anterior part of 

 the posterior zygapophyses. The inferior surface is slightly angulate, with 

 two low, latero-inferior ridges, and sometimes a low median one. The sur- 

 face between them is delicately reticulately sculptured. The neural arch 

 is oblique and highest behind. The combined neurapophyses rise rather 

 abruptly behind the anterior zygapophyses with an obtuse and convex 

 margin. They then descend in an arc to the extremities of the posterior 

 zygapophyses, diverging downwards and separated by an open groove, 

 which was doubtless the basis of attachment of the cartilage which repre- 

 sented the neural spine. External surface of the neurapophyses smooth. 

 The zygapophyses have little lateral expansion, but are well defined and 

 prominent antero-posteriorly. The processes which I have alluded to above 

 as diapophyses may not be such, as they are simply transverse expansions 

 of the anterior portion of the neurapophyses, whose posterior border articu- 

 lates with the lateral diapophyses of the centrum. 



"The basioccipital condyloid fossa is transversely hexagonal in outline, 

 the superior border being deeply notched by the superior portion of the 

 fossce chordcB dorsalis. The articular surface itself is funnel-shaped. The 

 parasphenoid bone advances far posteriorly under the basioccipital. It 

 expands into an acute angle on each side below the prootic, and then con- 

 tracts, so that its sphenoid region is narrower than its occipital extremity. 

 Its surface is slightly concave. 



"Measurements. 



M M 



"Depth of the maxillary bone at the Six posterior mandibular teeth in. .on 



middle of the nares 0.021 Transverse extent of glenoid cavity .012 



Width of the palatal surface at Transverse diameter of condyloid 



middle of the nares 014 fossa of occiput 019 



Six maxillary teeth at middle of Vertical diameter of do 013 



nares 014 Greatest width of parasphenoid 034 



Diameters of an anterior maxillary Thickness of do. at sphenoid portion .cx)35 



tooth 002 Three vertebrae (measured below) in. . 042 



Diameters of an anterior tusk of Chord of intercentrum 018 



the inner row 004 Length of intercentrum below oio 



Length of ramus mandibuli to an- Thickness of intercentrum below. . . .002 



terior border of interna ptery- Total length of neural arch 017 



goid fossa 058 Elevation of do. above posterior 



Depth of do. at do 023 zygapophyses 008 



Length of ramus mandibuli to pos- Expanse of anterior zygapophyses. .007 



terior border of internal ptery- Long diameter of lateral diapophysis .012 



goid fossa 015 Short diameter of lateral diapophy- 



Depth of ramus mandibuli at do. . .016 sis 005 



Depth of ramus mandibuli o.iio Length of rib 021 



from angle 016 Width of head of do 008" 



In the second paper Cope adds the description of the head: "The skull 

 is flat and rather wide, the length exceeding a little the transverse posterior 

 diameter. The posterior borders of the orbits mark a point half-way between 

 the extremity of the muzzle and the posterior supraoccipital border. The 

 orbits themselves are of medium size and are separated by a space about 

 equal to their transverse diameter. Their form is a wide oval, with the 

 long axis obliquely anteroposterior. The diameter of the external nostril 

 is nearly half of that of the orbit, and the form is similar to that of the 

 latter. The interorbital and ethmoidal regions are concave; the prefrontal 



