4 PEOCEEDINGS OF THE NATIONAL MUSEUM vol.69 



of Stenodelphis in their anteroposterior diameter. So far as the 

 present evidence goes, there are adequate reasons for considering 

 that the peculiarities of the type himbar of Pnscodelphi7ius stenus 

 indicates the presence of a porpoise in the Maryland deposits whose 

 skeleton will be found to possess vertebrae of a type not unlike those 

 of Stenodelphis. 



Measurements of the type vertebra {in millimeters) 



Length of centrum 39.4 



Breadth of centrum 26 



Height of centrum 26 



Minimum anteroposterior diameter of neurapophysis 25 



Breadth of neural canal 11-6 



Distance between sui>erior margin of metapophysis at base and top of 



centrum 16. 4 



Four other species, atropius, conradi, harlani, and spinosus are re- 

 ferred to Priscodelphinvs in the article in which stenus is described. 

 Cope subsequently withdrew four of these five species from the genus 

 Priscodelphinus. In 1875, Cope* referred Priscodelphinus stenus 

 to his genus Belosphys. Fifteen years later when Cope^ published 

 a list of the extinct Cetacea of North America, he again changed the 

 generic position of this species and referred it to IxacantTms. The 

 species stenus has remained in the genus Ixacanthus since that time. 



To summarize briefly the evidence in favor of the assumption that 

 this porpoise represents an undescribed form, it might be pointed out 

 that the transverse processes of the type caudal of Delphinapterus 

 ruschenbergeri are too slender to indicate any close relationship and 

 that the anteroposterior diameters of the neural spine, neural arches, 

 and transverse processes (at the base) of the type lumbar of 

 Priscodelphinus stenus are relatively greater. It is believed that 

 these differences are of sufficient importance to justify the application 

 of another name to the porpoise hereinafter described. 



KENTRIODON, new genus' 



KENTRIODON PERNIX, new species 



, INDIVIDUAL I 



Type specimen. — Cat. No. 8060, Division of Vertebrate Palaeontol- 

 ogy, United States National Museum. When this specimen was re- 

 ceived at the museum, it was seen that the skeleton was fairly com- 

 plete, with the skull, mandibles, cervical and dorsal vertebrae in their 



. * Cope, E. D., Synopsis of the Vertebrata of the Miocene of Cumberland County, New 

 Jersey. Proc. Amer. Philos. Soc., vol. 14, p. 36.3. 1875. 



* Cope, E. D., The Cetacea. American Naturalist, vol. 24, No. 283, p. 615. July, 1890. 



^KivTpiov, diminutive of Keyrpov, prickle or spike; 660)^ = 66065, tooth — in allusion to the pair 

 of elongated teeth at the extremity of the rostrum and mandibles ; pernUc, swift or nimble. 



