AN ATOM V OF MEGAPTERA LONGIMANA. 101 



General Survey of the Transverse Processes in B. muscidus. 

 Viewed from the caudal end and from above, the general outline of 

 the transverse processes shows but little of that convexity presented 

 by the processes of the lumbar and anterior caudal regions of Meg- 

 aptera, or by the whole sweep of the outline in B. borealis from the 

 neck to nearly tlie middle of tlie caudal region. In this B. musculus 

 the outline is nearly flat from about the 12th dorsal back to nearly 

 the end of the long lumbar region ; and along the caudal region the 

 outline tapers gradually backwards, with very little convexity. "If 

 compared to an ellipse, it would be the hinder half of a very narrow 

 ellipse, beginning at the 13th dorsal vertebra. Only the 13 or 

 14 posterior caudal vertebrae appear destitute of transverse pro- 

 cesses, giving a length of 4 J to 51 feet, as compared with the 7i feet 

 of Megaptera, without transverse processes. Viewed from the atlantal 

 end, the eye would take the 8th dorsal for the widest, and recognises 

 very little diminution on the 7th and 6th. The dorsal region as a 

 whole shows a figure bounded by a gently convex outline. Viewed 

 from above or below, the great breadth of the transverse processes 

 contrasts strongly with their little expansion in Megaptera. The 

 difference is least in the posterior lumbar region in Megaptera, but is 

 great throughout. ] 



Spinous Processes. 

 26. Form. — The most striking character of the spines in 

 Megaptera is their narrowness and but little of that expansion 

 at the end which B. musculus shows to so great an extent. 

 This may be in part owing to incomplete ossification in this 

 Megaptera, but the exposed surface from which the cartilage 

 has been removed belongs to the top with a tapering prolonga- 

 tion below the posterior angle for about 1 inch only. Further 

 ossification would increase the length, but it could not well 

 give a terminal expansion so great as in B. musculus, so as to 

 bring the expanded ends nearly in contact, or actually so, for 

 from 3 to 5 inches down from the top. Taking the last dorsal 

 vertebra, the breadths at the middle and at the end are — in 

 Megaptera, 4| and 5i inches ; in B. musculus, 5 j and 8^. In 

 the articulated skeleton the intervals between the end of the 

 dorsal processes are fully 2 inches, while in B. musculus the 

 expanded ends may be in contact or about 1 inch apart. 

 Rudolphi's figure of the skeleton of Megaptera shows the spines 

 almost square-topped, and not broader at the top than at the 

 middle. In the figure of the skeleton by Van Beneden and 

 Gervais (pis. x. and xi.) the tops of the spines are less rounded, 

 but not more expanded than in this Megaptera. Their figure of 



