50 AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



"It is uncertain whether there is a process at the inner side of the tabu- 

 lare as in Z. serratus. The region of the occipital condyle is without pro- 

 jection and is like that of other species of the genus." 



Revised description: This is contained in the description of the genus. 

 The two species are indistinguishable in the known specimens. The dif- 

 ference in size of the orbits mentioned by Cope is not apparent after the 

 specimens have been cleaned. There are more prominent serrations on the 

 supraoccipital plate of the specimen called Z. serratus, but their absence 

 from other specimens may easily be the result of conditions of fossilization. 



Zatrachys conchlgerus Cope. 

 Proc. Am. Phil. Soc, vol. zzxiv, 1896, p. 453. 



Type: The posterior portion of a small skull. No. 4590 Am. Mus. Nat. 

 Hist. Cope Coll. From Texas. 



Original description: "This ganocephalous batrachian is known to me 

 from the posterior part of the cranium of an individual about the size of the 

 smaller specimen of the species just described (Zatrachys micropthalmus). 

 It diifers from this and from the Z. serratus in two conspicuous characters. 

 First, the tabular processes are smaller and more widely separated from 

 each other; second, the border of the quadratojugal element projects freely 

 from the distal part of the quadrate, and is separated by an open emargina- 

 ation. The orbits are not so small as in Z. micropthalmus, have a raised 

 border, and are posteriorly placed. Their diameter is about equal to the 

 space between their posterior border and the tabuloquadrate notch, and 

 is about half the interorbital width. The tabular processes are quite small, 

 and the border connecting them is depressed in the center. The surface is 

 strongly rugose. 



"The occipital condyles are represented by two shallow cotyli, which 

 are confluent on the middle line. The posterior part of the pterygoid forms 

 a sharp curve inwards before reaching the quadrate, and presents a thin 

 edge inferiorly. The free edge of the quadratojugal is serrate. The muzzle 

 of this specimen is broken off a short distance anterior to the orbits. 



"Dimensions. mm 



"Width at quadrates 56 



Width at quadratojugals 74 



Width between orbits 20 



Width between tabular processes 25 



Diameter of orbit 10" 



Revised description: This poorly preserved fragment shows only that por- 

 tion of the skull posterior to the orbits, and is covered with a hard matrix. 

 The orbits are in the same relative position as in Zatrachys serratus. The 

 posterior ends of the tabulare are broken off and so the length can not be 

 given. There is a deep emargination of the posterior separating off the 

 quadratojugal; this is apparently natural, but the condition of the specimen 

 makes it impossible to determine whether the bones have been broken or not. 



The species is indeterminate and must remain doubtful until further 

 information is gained by discovery. 



Zatrachys apicalis Cope. (See Aspidosaurus apicalis Cope, page 6;.) 

 Zatrachys crucifer Case. (See Aspidosaurus eruciftr Case, page 66.) 



