114 



AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



rounded by elevated ridges. Just anterior to the orbit is a deep depression, 

 not a fenestra; the posterior and inner sides are nearly vertical, but the outer 

 parts open gently on the sloping surface of the skull, and extend to the narial 

 opening anteriorly. 



The nares are located far back and look almost directly upward. They 

 are separated from the depression behind by a slight ridge and from the 

 depression of the median region of the skull by the extension of the longi- 

 tudinal ridge described, which does not, however, reach to the anterior end 

 of the skull. From the nares forward the surface of the skull is perfectly 

 flat and a little lower than the edge; this depressed area joins that of the 

 median facial region anteriorly. A strong ridge passes from orbit to orbit, 

 not terminating the facial depression, as described by Cope, but_ separating 

 it from a similar, but less pronounced depression behind, in which lies the 



parietal foramen. The sides of the tem- 

 poral region slant steeply outward and 

 downward (see fig. 8, a and b). 



The maxiJlary bone is very slender, 

 but its posterior termination can not be 

 made out. The teeth are small and con- 

 ical, and no palatine tusks can be made 

 out in the specimens, though they may 

 have been present. The edges of the 

 maxillary extend straight out beyond the 

 tooth line, like the overhanging eaves 

 of a roof. 



The quadrate is not determinable; 

 it may have been a small element con- 

 cealed by the surrounding bones, as in 

 Eryops. The articular region of the lower 

 jaw fits into a deep depression of the 

 skull. The surface of the parasphenoid 

 and pterygoids exposed is covered with 

 minute teeth. 



The position and relations of the 

 bones determined are shown in fig. 43 b. 



A small scapula associated with bones of Zatrachys probably belongs 

 to the genus. The form is shown in fig. 43 d and e. 



Von Huene has recently redescribed the skull of Dasyceps bucklandi 

 Lloyd, from the Permian of Kenilworth in England (55). A comparison 

 of fig. 44, reproduced from v. Huene's paper, with figs. 8 b and 43 b 

 shows how great a similarity exists between the two forms. The genus 

 Dasyceps seems to lack the deep pits between the orbits and the nares, and 

 Zatrachys does not have the median opening between the nares, but in other 

 respects the skulls are almost identical. It is apparent that both genera are 

 highly specialized members of groups which had advanced far \n the pecu- 

 liar development of excrescences and ornamentation characteristic of the 

 Permian or upper Carboniferous. It is perhaps not justifiable to place these 

 forms in a common family, but the separation can not be very great. 



A larger skull than any described by Cope (No. 4873 Am. Mus. Nat. 

 Hist.) is probably a Zatrachys, but is covered with a hard, refractory matrix. 

 Total length on mid line, 137 mm. 



Fig. 44. — Dasyceps huMandi. 

 skull from von Huene, 



Restoration of 

 XX. 



