SYSTEMATIC REVISION 33 



seem to be differences too great to permit this. The skull is small and the 

 creature could not have been over half a meter long at the greatest. The 

 orbits are proportionately large. The nares more nearly terminal than in 

 Eryops and nearer to the lateral edge. The angle of the jaw is continued 

 beyond the quadrate. The lower jaw is much narrower, vertically, than 

 in Eryops. 



Genus ANISODEXIS Cope. 

 Proc. Am. Phil. Soc, vol. xx, 1882, p. 459; Am. Nat., vol. xviii, 1884, p. 36. 



Type: A few fragments of a skull. No. 4556 Am. Mus. Nat. Hist. 

 Cope Coll. From Texas. 



Original description: "Class Batrachia; order Rhachitomi; family Ery- 

 opidse. Teeth on premaxillary, maxillary, and dentary bones of unequal 

 lengths, some very large, others very small. Dentinal inflections straight, 

 nearly reaching the pulp cavity. Cranial surfaces sculptured. 



"This genus differs from all the others of the Eryopidce, in the great and 

 abrupt inequality of the teeth of the external series of the mouth, resembling 

 in this respect some of the Saurians of this deposit, rather than the batrachia. 

 Whether it possesses long palatine or pterygoid teeth, such as most of the 

 latter exhibit, is not rendered clear by the specimens, but appearances 

 indicate the presence of one near the anterior part of the maxillary. Man- 

 dibular series simple." 



In the second paper the description is as follows : 



"The genus differs from those previously described in the inequality of the 

 size of the teeth of the external series. Thus in the upper jaw there is a very 

 large one near the symphysis. The neural arch of the vertebrae resembles 

 that of the genus Acheloma. The A. imbricarius Cope is the only known 

 species, and is represented in the collection by fragments only. The size 

 of the skull is nearly that of Eryops megacephalus. The sculpture of the 

 superior surface of the skull is a coarse reticulation; that of the sides of the 

 jaws is of an imbricate or shingle-like pattern. The vertebrae do not exhibit 

 an expansion of the neural spine." 



Anisodexis imbricarius Cope. 

 Proc. Am. Phil. Soc, vol. xx, 1882, p. 459. 



Type: The same as the genus. 



Original description: " Founded on numerous fragments of the skull with 

 jaws, and a vertebral arch and spine found in connection with the remains 

 of the Diplocaulus magnicornis. These pieces indicate a larger species than 

 the latter, and are nearly equal to the Eryops megacephalus. The jaws are 

 not preserved entire, but portions from different parts of the length display 

 the dental characters. 



"The sculpture of such parts of the superior surface of the skull is a coarse 

 reticulation, coarser than in any other species known to me. _ Near the edges, 

 some of the bones become smoother, and the ridges flatten into overlapping 

 lamina. The entire sculpture of the dentary bone is of this imbricate char- 

 acter, the apparent overlapping being from before backwards, and below 

 upwards. This is totally different from what is observed in the other known 

 species of Eryopidce, Trimerorhachidce, and Diplocaulidce. The teeth are 

 round in section, but become lenticular near the apex, developing low cut- 

 ting edges. The basal grooves are fine, but distinct, and extend half-way 



