76 PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. 



posterior end of the pterygoid, the posterior lower edge of which extends to within 

 8 mm. of the condylar margin. The condyle is transverse, the inner side descend- 

 ing lower than the outer, with a trochlear groove in the middle. The posterior 

 part of the pterygoid, beyond the dentigerous plate, is a thin, flat, or gently con- 

 cave process, articulating at its extremity with the quadrate, as described. On 

 the right side, lying on the outer side of the quadrate expansion, which is here 

 exposed, there is a smooth rod, expanded above, where it lies in juxtaposition with 

 the parietal; more slender below, its lower end doubtless dislodged from its original 

 position above the dentigerous plate. It must be the epipterygoid. 



The occipital condyle is gently convex, subcordate in outline, with the usual 

 notochordal pit in the middle. On either side of the foramen magnum there is a 

 projection having, apparently, an articular facet, doubtless for articulation with a 

 proatlas. On the side of the skull there was a slender temporal bar like that of 

 the skull described in the preceding pages, the most of which was broken away 

 and the pieces lost. Its free, thin border curves downward posteriorly to very 

 near the condylar margin of the quadrate, with which the bone articulates. Broom's 

 conjectural restoration here is incorrect ; the free border of what he supposed was a 

 foramen in the arch is merely the lower border of the temporal arch ; and there are 

 no indications on the smooth surface here of a suture distinguishing a quadratojugal. 



From the two specimens of skull figured herewith it will be seen that the 

 conjectural restorations of Edaphosaurus were both incorrect ; in some details that 

 of Case is the better, in others that of Broom. The orbit is not as large as Broom 

 figures it; the quadrate descends much lower; the single temporal vacuity is of 

 a different shape; there is no foramen in the temporal arch; the whole skull is 

 narrower and higher, and there is no palatine vacuity. Broom was probably more 

 nearly correct in the sutures of the face; Case in those of the frontal region. Case 

 was also apparently correct in the detection of the bone in the occipital region 

 called by him " ? epiotic." The sutures everywhere need corroboration, and 

 otherwise should not be accepted as certain. 



VertebrcB (fig. 48) : Fifteen vertebrae were found in a continuous series articulated 

 with the skull, and their matrical attachments have been preserved in preparation. 

 The posterior three are more or less fragmentary, and the spines of the posterior 

 eight, which were exposed when discovered, are more or less wanting. Only a 

 fragment of the atlas has been detected. As in most of the Pelycosauria, the first 

 six of the vertebrae, counting the altas, may be considered as cervicals. With the 

 seventh a much heavier rib was articulated, and it doubtless was the first thoracic 

 vertebra. As in the different species known as Naosaurus, the cervical vertebrae 

 are remarkable for their decrease in size, as also for their much shorter ventral 

 lengths. To such an extent, indeed, are these vertebrae shortened on the under 

 side that closely articulated the skull would be directed obliquely downward and 

 backward. The twelfth vertebra, of much larger size, has its articular ends nearly 

 parallel with each other, while those of the first two or three vertebras are inclined 

 in such an angle that the lower border is a third shorter than the longitudinal 

 diameter on the floor of the neural canal, and is but little more than half the length 

 of the lower border of the twelfth vertebra. Throughout the cervicals the lower, 

 concave border is sharply keeled ; further back, the lower side is more obtusely 

 keeled. The anterior diapophyses, beginning with the axis, are more slender, but 

 as long as those further back. In the cervical region they are directed downward 

 and backward; posteriorly they are more transverse in position and are situated 

 near the front end of the vertebra. The zygapophysial surfaces of the cervicals 

 are extensive and nearly horizontal in position. The zygapophyses of this region 



