350 



ME. W. H. FLOWER ON THE OSTEOLOGY OE THE SPEKM-WHALE. 



the transverse processes, which pomts to a close aihnity with Hyperoodon and the 

 Ziphioids. The lumbar and caudal regions also, in some characters, especially their 

 short transverse processes, approximate to those of the same forms ; the spinous pro- 

 cesses, however, fall far short of the excessive height, and the bodies of the vertebra; 

 present but little of the peculiar elongation, so characteristic of those groups. 



Chevron Bones. 



Ten chevron bones were sent with the skeleton ; but it would appear from the distance 

 to which these bones extend backwards, as ascertained with certainty on the detached 

 tail described at p. 347, that fourteen is the complete number. By a careful comparison 

 of the articular surfaces on the vertebrse with those on the different chevron bones, the 

 missing ones were ascertained to be the fifth, sixth, and the thirteenth and fourteenth. 



The first (See PI. LIX.) is represented by a pair of small styliform bones. They are 

 not quite alike, the right being rather the longest,. and the left much the thickest. 

 They both end in a point, and are slightly hollowed on their inner side, and flattened 

 externally. They fit most closely, by an expanded, rough, subcircular base, to the corre- 

 sponding facets on the hinder margin of the body of the first caudal vertebra. The 

 dimensions of these bones are : — 



From the Yorkshire skeleton these bones are absent. In the Caithness specimen 

 they are more massive and irregular in shape, and are completely ankylosed to the body 

 of the vertebra. Their free extremities diverge from each other and project strongly 

 backwards. 



In the succeeding bones (up to the fourteenth) the two lateral lamina are united 

 below, and form a prominent spine. The second is comparatively small and narrow, 

 and has the spine slightly developed. In the third the spine is very large, both long 

 and broad, and truncated below. In the fourth it is somewliat shorter, but more mas- 

 sive and rounded at the lower end. The entire length of the second bone is lOf", of 

 tlie third 21", and of the fourth 20". The lower edge of nearly all the remaining bones 

 has been cut off by a sharp instrument in preparing the skeleton ; so I am not able to 

 give their correct length or configuration. The surfaces for contact with the vertebrae 

 are expanded, massive, rough, and hollowed ; and many of them have imbedded within 

 them separate epiphysial ossifications, more or less ankylosed either to the chevron 

 bone or to the body of the vertebra. 



In both the Caithness and Yorksliire skeletons the number of the chevron bones is 



