EASTMAN : TYPES OF FOSSIL CETACEANS. 



93 



Cervical Vertebrae- — The entire series of cervicals is preserved, together with 

 portions of the first three dorsals, all in natural association. Their features may 

 be best described by saying that they reproduce in strikingly similar manner 

 those of the corresponding structures in Iuia, the resemblance being much closer 

 than with any other genus. This similitude is found in the form of the individual 

 vertebrae, their relative size, and arrangement with respect to each other, espe- 

 cially as regards the undulating overlap of the neural arches. Saving only that the 

 atlas is more transversely elongate in Lophocetus than in the modern genus, it 

 might be referred with equal propriety to either, if found in the detached con- 

 dition. In both forms, the suboval ring of the atlas is of considerable thickness, 

 with feeble neural spines and abbreviate transverse processes, the latter pointed 

 slightly upward and outward, and provided below with a large flattened hypapo- 

 physial process for articulation with the axis, which has, of course, no distinct 

 odontoid process. Owing to abrasion of the neural arch in the axis and third 

 cervical vertebra, their spinous processes, such as they were, have been entirely 

 destroyed ; and the same is true for the last cervical and first three dorsals. All 

 of the intervening cervicals, however, retain traces of very feebly developed neural 

 spines. 



On the under side of the series are seen in cross-section the stumps of the 

 downwardly directed transverse processes, now broken off, belonging to the fifth 

 aud sixth cervicals. Their relations are apparently identical with those in Inia. 

 On the inferior side, also, the size of the different centra is displayed to best 

 Measurements taken here of these bodies are given as follows: — 



advautage 



Length of 1st cervical vertebra 

 it 2d " " 



" 3d 



4th " " . 

 5th " " . 

 6th " " . 

 7th " " . 

 1st dorsal 

 " 2d " " 

 Height of atlas 



axis 



7th cervical vertebra 

 Width of atlas including processes 



axis 



3.0 em. (approximately) 



2.0 " 



0.6 " 



0.8 " 



0.7 " " 



0.8 " 



1.3 " 



1.8 " 



2.3 " " 

 8.2 " " 

 6.2 " 



6.4 " " 

 12.4 " 



10.0 " " 



Delphinus occiduus Leidy. 



Plate 4, Fig. 1. 



The second type specimen to be considered, although referred by Leidy, who 

 first described it, unqualifiedly to the genus Delphinus, is to be understood rather 

 as belonging to the group of Dolphins proper, that is, to the subfamily Delphinae, 

 than as embraced within the more circumscribed limits of the typical genus. This 



