R. S. Lull — Fossil Dolphin from California. 215 



massive bone, and exhibits again the posterior face of the cen- 

 trum, which is concave with well-rounded margins. The axial 

 arch and spine, the former exhibiting a well-developed post- 

 zygapophysis upon the left side, are well preserved but appar- 

 ently entirely detached from the centrum. 



I can discern with fair assurance the impressions of five or 

 six cervicals in proper sequence, but what is apparently the 

 sixth shows a diapophysis comparable in development to that 

 of the seventh in Delphinus, while just beyond it there lies an 

 impression very suggestive of the diapophysis which in the 

 modern form articulates with the tuberculum of the first rib ; 

 one cervical is therefore either missing or too obscurely defined 

 to be recognized. 



In comparison, then, with Delphinus, the fossil again exhibits 

 more generalized traits in the free cervicals, in their actually 

 greater length in the smaller specimen, and their much greater 

 relative size. They seem to represent more nearly the degree 

 of evolution shown by Inia, but display no feature which 

 would debar the older type from direct ancestry to Delphinus. 



Measurements of the cervical series. 



Delphinavus Delphinus 



Cat. No. 10040 Cat. No. 265 



Length of entire series 74mm* 417mm 



Width of atlas _. 62-5 119 



Height of axial spine measured from base of 



postzygaj>ophysis -- 46 40 



Dorsal vertebras. — At least twelve rib-bearing vertebrae are 

 preserved, comparable in number to those of Phocazna, and 

 three fewer than in Delphinus delphis. However, this is of 

 little moment, as the remainder of the body is lacking in the 

 fossil so that the number of dorsals and 

 ribs may readily have been greater. Fig. 4. 



The vertebrae differ markedly from 

 those of either of the above mentioned 

 genera in the much greater length of 

 centrum and in the low neurapophysis 

 in contrast with the very high spine of 

 an approximately equivalent vertebra of ' 



the recent form. The proportions of 

 the vertebral centra are more nearly jp IG . 4, % Ninth dorsal 

 those of Inia again, though in that genus vertebra, left aspect. % 

 the neutral spine is much higher. " nat - size - Im ^-. imprea- 



1 ° sion. 



* This is not a just measurement, for the vertebrae are slightly displaced. 



