16 SrSTEMATIC PALEONTOLOGY 



diapophyses of the caudal and lumbo-sacral vertebrae, but differs from 

 it and all other Delphixidae with which I am acquainted in the man- 

 ner of the attachment of the epiphyses of the vertebrae. Instead of 

 being nearly plane and thin discs, they are furnished with two oblique 

 faces above, which are capped by a projecting roof formed by the floor 

 of the neural canal, while their central portion forms a knob which 

 fits a corresponding shallow pit of the centrum." 



IXACANTHUS CONKADI (Lcidy). 



Delphinus conradi Leidy, 1852, Proc. Acad. Nat. Sci. Phila., voL vi, p. 3.5. 

 Delphinus conradi Cope, 1867, Proc. Acad. Nat. Sci. Phila., vol. xix, p. 144 



(mention only). 

 Priscodelphiiius conradi Cope, 1868, Proc. Acad. Nat. Sci. Phila., vol. xx, p. 188. 

 Priscodelph'mus conradi Leidy, 1869, Jour. Acad. Nat. Sci. Phila., 2nd ser. , vol. vii, 



p. 4o3 (mention only). 

 BelospMjs conradi Cope, 1875, Proc. Amer. Philos. Soc, vol. xiv, p. 363. 

 Ixacatithns conradi Cope, 1890, Amer. Nat., vol. xxiv, p. 614. 



Description. — The species was described by Leidy in 185'2 from a 

 single lumbar vertebra. " The epiphysial extremities of the vertebrae 

 are pentahedral. 



Length of vertebral body 2^ inches (55 mm.) 



Breadth of epiphysial extremities If inches (43 mm.) 



Breadth of base of transverse process. . . .If inches (43 mm.)" 



In 1868 Cope added from additional material : '' Its affinities are 

 apparently nearer the last mentioned species (P. harlani) than any 

 other." 



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

 ent river. 



Collection. — The type specimen was probably placed in the museum 

 of the Academy of Natural Sciences of Philadelphia but seems to be 

 lost. Cope's specimens are there. 



IXACANTHFS STENUS Cope. 



Plate XIII, Figs, la, lb. 



Priscodephinus stenus Cope, 1868, Proc. Acad. Nat. Sci. Phila., vol. xx, p. 188. 

 Priscodephinus stemis Leidy, 1869, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. vii, p 



433 (mention only). 

 Belosphys stenus Cope, 1875, Proc. Amer. Philos. Soc, vol. xiv, p. 363. 

 Ixacanthun stetins Cope, 1890, Amer. Nat., vol xxiv, p. 614. 



