18 A REVISION OF THE COTYLOSAURIA OF NORTH AMERICA 



' ' Measurements. 



"No. I. M 



"Length of last six superior molars °-°55 



Diameters of antepenultimate molar: 



Anteroposterior 0I ° 



Transverse 02 ° 



Diameters of crown of incisor: 



Vertical 0I 3 



Transverse (at base) 00 7 



Anteroposterior 0I1 



"No. 2. 



Length of dental series in a straight line 093 



Width of palate at anterior expanse 062 



Width of palate at contraction °68 



Width of palate between widest molars 03 d " 



Revised description: It is evident that in his description Cope mistook the lower 

 jaw for the upper; the mistake is very pardonable, as the bones are badly crushed 

 and the basisphenoid and basioccipital bones lie between the jaws. The teeth 

 resemble those of D. molarts; the median cusp is wedge-shaped, extending across 

 the crown; the outer cusp is wider than the inner; both the inner and the outer cusps 

 are separated from the median one by a nearly flat space. The outer cusp is crossed 

 transversely by a sharp, very narrow groove which practically divides it into two 

 tubercles. This groove is visible on the outer but not on the inner side of the median 

 cusp. The inner cusp is divided less perfectly by a wider and more shallow groove. 

 In the upper teeth the cusps are divided by wide and shallow grooves. 



Empedias alatus Cope.* 

 Proc. Am. Phil. Soc., vol. xvii, 1878, p. 516. 



Type: Several vertebra?, the same as the genus. 



Original description: "The diapophyses are not long, and their articular sur- 

 faces are quite elongate downwards and forwards, especially on the cervical centra. 

 On the more posterior dorsals, the diapophysis arises exclusively from the neural 

 arch, but maintains its very narrow oblique articular face. On all the vertebrae the 

 centrum is about as long as wide, with regular marginal angles without bevel for 

 intercentrum. The sides are concave, and the inferior median line horizontal, and 

 thickened. The neural spine is short in the dorsals, and with a subquadrate section, 

 with the angles lateral and anteroposterior. The apex is excavated at the extremity. 

 The space between the planes of the opposite zygapophyses is strongly convex. The 

 latter have horizontal faces. In other vertebras the neural spine is more transverse, 

 and the zygapophyses are separated on the median line by a smaller fossa on the 

 anterior face of the arch and a larger one on the posterior face. 



" In a specimen in which the hyposphen has disappeared, it is represented by a 

 ridge connecting the posterior zygapophyses, which is decurved over the neural canal. 



" Measurements. 

 "No. 1, dorsal vertebra of the smaller individual. M 



"Total elevation of the vertebra 0.105 



Elevation of the centrum 029 



Elevation of the zygapophyses °6° 



Elevation of the base of neural spine °°3 



Width of apex of neural spine 02 S 



♦This species appears in Cope's lists of 1881 and 1888, but after that is not listed by him, as it became apparent that it was 

 indeterminate. 



