KENTRIODON PERNIX, A MIOCENE PORPOISE FROM 



MARYLAND 



By Remington Kellogg 

 Of the Bureau of Biological Survey, United States Department of Agriculture 



After having recently reexamined the types of the fossil porpoises 

 described from the Miocene formations of Maryland and Virginia, 

 the problem of allocating some of these species arose and this in turn 

 led to a reconsideration of several undescribed specimens in the 

 National Museum. Among Cope's types are two porpoises, Delphin- 

 apter'us ruschenhergeri'^ and Pnscodelpkinus stenus,^ with vertebrae 

 of ai:)proximately the same size as those of the porpoise described in 

 this paper. After some study it was decided that, on the basis of 

 vertebral characters, one of these porpoises may be related or refer- 

 able to the genus Delphinodon and that the other appears to have 

 more features in common with the living genus /Stenodelphis than 

 with any other porpoise. The vertebrae of these two porpoises have 

 some very distinctive features and it was deemed advisable to dis- 

 cuss them more fully in this connection and to point out the essen- 

 tial peculiarities which seem to distinguish them from those of the 

 porpoise hereinafter described. 



DELPHINAPTERUS RUSCHENBERGERI Cope 



The fossil porpoise Delphinapterus ruschenhergeri was based upon 

 a lumbar and a caudal vertebra (Cat. No. 11233, Academy of 

 Natural Sciences of Philadelphia) ; they may have belonged to a 

 porpoise in the same genus as Delphinodon dividuni, but this is un- 

 certain. On both of these small vertebrae the basal portions of the 

 comparatively long transverse processes are preserved. The anterior 

 and postea'ior margins of the right transverse process of the type 

 lumbar are eroded and one can not be certain whether the transverse 

 processes were like those of Kentriodon which have expanded ex- 

 tremities or like the attenuate type exemplified by Delphinodon 

 dividMin. The centra of these vertebrae are long — not short and 



1 Cope, E. D., Second contribution to tlie history of tlie Vertebrata of the Miocene 

 period of the United States. Proc. Acad. Nat. Sci. Philadelphia, TOl. 20, p. 189. July, 

 1868. 



= Cope, E. D., Idem., p. 188. 



No. 2645.— Proceedings U. S. National Museum, Vol. 69. Art. 19. 



2994—27 1 1 



