48 



A REVISION OF THE COTYLOSAURIA OF NORTH AMERICA 



bones sculptured. Frontal bone bounding the orbit above. This genus displays 

 in this family the character found in Lepidosternum and other genera among the 



Amphisbcenidcz. The large superiorly placed 

 orbits and inferior posterior mouth indicate that 

 the animal lived in some locality where upward 

 vision was important, while its food was below 

 it." 



A glance at the specimen (see fig. n) shows 

 that there are really two skulls present. The 

 larger one is probably a species of Captorhtnus 

 and the smaller, which is held in the mouth of 

 the larger, is that of a small amphibian. The 

 small skull is inverted so that the orbits, which 

 Cope described as the large inferior nares, lie on 

 the lower side of the larger skull. The apparent 

 shortness of the lower jaws of the larger skull is 



Fig. II. — -Two views of the two specimens called 

 Hypopnous squaliceps by Cope. X |. No. 4335 

 Am. Mus. 



due to their having been shoved backward by crushing. 

 The genus and species must be dropped. 



Genus HELODECTES Cope. 



Proc. Am. Phil. Soc, vol. xix, 1880, pp. 45 and 48. 

 Proc. Am. Phil. Soc, vol. xxxv, 1896, p. 442. 



Type: A left maxillary and probably premaxillary bone. No. 4346 Am. Mus. 

 Nat. Hist. Cope Coll. From Texas. 



Original description: In 1 880, p. 45, Cope distinguishes the genus Helodectes 

 from Diadectes and Empedocles by the presence of two rows of molar teeth. On 

 page 48 of the same article he states that the characters are in general the same as 

 those of the family Diadectidce. He adds that there is apparently a large tooth in 

 the position of an anterior incisor in the typical species. In 1896 he states that the 

 genus probably belongs to the family Parwtichidce. 



Revised description: The material upon which this genus is based is so imper- 

 fect as to make it very doubtful if a second specimen could be determined with 

 confidence. The numerous teeth in the fragment of the jaw indicate a member of 

 the suborder Pareiasauria, but the fragment and the roots of the teeth indicate an 

 animal much larger than any well-known member of the suborder. The genus is 

 retained provisionally. 



Helodectes isaaci Cope. 



Proc. Am. Phil. Soc, vol. xix, 1880, p. 49. 



Type: A fragment, probably of a maxillary bone, lacking both ends and con- 

 siderably obscured by matrix. From Texas. 



Original description: "The bases of the teeth of one of the rows are much more 

 expanded transversely than those of the other, having the form of some of those of 

 Empedocles. As in that genus, they shorten anteriorly. In the fragment I count, 

 on this row, bases of nine teeth. In the other row I can only definitely count three, 

 which are opposite the second, third, and fourth of the other series (counting from 

 behind). They are wide transverse ovals, about half the long diameter of the poste- 

 rior teeth of the other series. 



