10 SYSTEMATIC PALEONTOLOGY 



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

 ent river. 



Collection. — The type specimen is in the Museum of the Academy 

 of Natural Sciences of Philadelphia. It bears the label " Tretosphys 

 gabbi Cope (Delphinapterus, Cope, type). Caudal vertebra, E. D. Cope, 

 Charles Co., Md." 



Peiscodelphinus ruschenbergeei Cope. 

 Plate X, Pigs. 7, 8. 



Delpfimapterus ruschenbergeri Cope, 1868, Proc. Acad. Nat. Sci. Phila., vol. xx, p. 



189. 

 Tretosphys ruschenbergeri Cope, 1869, Proc. Acad. Nat. Sci. Phila., vol. xxi, pp. 7-9. 

 Tretosphys ruschenbergeri heiAy, XSQ'i, Jour. Acad. Nat. Sci. Phila., 2nd ser., vol. 



vii, p. 434 (mention only). 

 PriscoHelphinus ruschenbergeri Cope, 1890, Amer. Nat., vol. xxiv, p. 615, 



Description.— l^h\& species was about the size of Ixacanthus stenus. 

 " They (the vertebrae) are also of a slender form, more so than in any 

 species of the last genus (Ixacanthus). What distinguishes it generally, 

 is that instead of the slender diapophyses of the caudal it has the broad 

 ones of the true Dolphins, though broader even than is usual in these, 

 and it is perforated a little on one side of the middle by the foramen 

 seen among the whales and dolphins generally. 



" Articular faces transversely oval; centrum slightly constricted with 

 an obtuse keel along the median line. The two inferior keels of the 

 caudal vanish on the middle part of the centrum. 



Length of centrum 1 in. 9 lines (-68 ram.) 



Height of centrum 10.3 lines (^^.6 mm.) 



Width of centrum 12.5 lines (25 mm.) 



Width neural canal 5.2 lines (10.4 mm.) 



Width basis diapqij)hysis lumbar 10.5 lines (21 mm.) 



Width basis diapophysis caudal 10 lines (20 mm.)" 



The type specimen consists of two vertebrae, a lumbar and a caudal 

 vertebra. 



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

 ent river. 



Collection. — Philadelphia Academy of Natural Sciences. 



