MARYLAND GEOLOGICAL SURVEY 19 



This species differs from P. harlani in that the dorsals are less 

 depressed, stouter and lack the inferior keel. There were three speci- 

 mens considered in the formation of the species, representing among 

 them vertebrae from the dorsal, lumbar and caudal regions. 



Occurrence. — Calvert Formation. Charles county near the Patux- 

 ent river. 



Collection. — Philadelphia Academy of Natural Sciences. 



Ixacanthus coelospondylus Cope. 

 Plate XIV, Figs. 1, 2. 



Ixacanthus coelospondylus Cope, 1868, Proc. Acad. Nat. Sci. Phila., voL xx, pp. 159, 



187. 

 Ixacanthus coelospondylus' Leidy, 1869, Jour. Acad. Nat. Sci. Phila., 2nd ser., voL 



vii, p. 435 (mention only). 

 Ixacajithus coelospondylus Cope, 1890, Amer. Nat., vol. xxiv, p. 614. 



Description. — In the report of his verbal communication Cope stated 

 that the " form was allied to Priscodelpliinus in its slender and pointed 

 diapophyses of the lumbar and caudal vertebrae, but differed in the 

 concave centrum, with four processes clasping the epiphysis." 



The specific description is as follows : " Extremities of the centra 

 deeply concave when epiphyses are removed; length of vertebrae less 

 than breadth. 



Length of centrum lumbar 2 in. 4.5 lines (59 mm.) 



Width centrum lumbar 2 in. 6.5 lines (63 mm.) 



Elevation centrum lumbar 2 in. 4 lines (58 mm.) 



Width neural canal on dorsal. . . .1 in. (25 mm.) 



Width neural canal on lumbar ... .45 lines ( .9 mm.) 



Length caudal vertebrae 2 in. 6 lines (62 mm.) 



Transverse diameter 2 in. 3 lines (56 mm.) 



Width diapophysis at base 6 lines (12 mm.) 



Lumbar, elevation of body and 



spine to anterior zygapophyses.4 in. 9.5 lines (119 mm.)" 



In the American Naturalist, Vol. XXIV, 1890, Cope remarks that 

 this species was short and robust; about the size of the White whale 

 {Beluga). 



