190 PROCEEDINGS OF THE ACADEMY OF 



This species is dedicated to W. S. W. Rusclienberger, M. D., of this city, 

 an active member of the Academy, and author of introductory works on 

 Natural History. 



Delphinapterds lacertosus Cope. 



This is much the largest species of the genus. It is based on two lumbar 

 vertebrte which have been united by an exostosis and then separated. They 

 are quite elongate and have broad diapophyses so far as their bases indicate. 

 The articular surfaces are about as broad as deep, and slightlj' pentagonal in 

 outline, not ovoid or discoid as in other species. The lower surface presents 

 an obtuse median angle, with slightly concave sides. The general proportions 

 can be derived from the measurements. 



In. Lin. 



Length centrum 3 5-5 



Heighth articular surface 2 2-5 



Width '' " 2 4-5 



" neural canal V-S 



" base diapophysis 1 9 



In addition to the above, there are in the Museum of the Academy speci- 

 mens of dorsal lumbar and caudal vertebras of this species from the Miocene 

 of Cumberland county, New Jersey. They all belong to one individual and 

 represent the characters of the species well. The lurabars are all strongly 

 keeled below, and the dorsals narrowly rounded, and slightly concave on each 

 side. One posterior caudal, with rudimental anterior zygapophyses exhibits 

 rather short diapophyses pierced by the vertical foramen. I therefore refer 

 this species to Tretosphys with the remark, that it is not so typical as the first 

 mentioned species, where the perforation is at the middle of a broad, well 

 developed transverse process. 



The two species which follow are assigned to this genus, only on account of 

 their resemblance to the present one, as I have not seen the caudal vertebrse of 

 either. They may be thought to rest on but a slight basis — but as they are 

 extremely easily distinguished among several bushels of bones of other species, 

 I feel entire confidence in their reliability. 



Delphinapterus tyranncs Cope. 



This is a large species, doubtfully of the genus, not uncommon in the 

 Miocene formations of Maryland. It is represented in the collection by one 

 dorsal and three lumbars. Three of these serve as the type of our diagnosis. 

 They are much shorter in relation to their other dimensions than those of any 

 other fossil dolphin h erein described, except the Ixacanthi,and they have the broad 

 diapophyses of the genus Delphinus. The epiphyses are unfortunately lost, 

 and but three of the specimens belong to the same individual. Articular sur- 

 faces broader than high, latery faces concave everywhere and in every direc- 

 tion ; below they meet in an obtuse concave ridge. 



In. Lin. 



Length centrum lumbar (epiphyses supplied) 3 



Depth " 2 10-5 



"Width " 2 3-2 



" neural canal 6-7 



" basis diapophyses 2 0-5 



Length lumbar of larger individual 



The rugosity of the epiphysial surfaces is less marked and more intrerupted, 

 i. e. without radiating ridges, than in any other species. 



Delphinapterus hawkinsii Cope. 



This species is based on two lumbar veterbras, which resemble those of P- 

 conradi, {Delphinus conradi Leidy), but are of much larger size and are 

 furnished with a strong and acute keel below on the median line, as is seen in 

 no other species. The diapophyses are very wide at the base ; centrum much 



[July, 



