OF BAL^NOPTERA MUSCULUS. 229 



This table is, of course, open to objection on the score of perfect accuracy ; but it shows 

 clearly that if drawings of all these were placed together, that the diversity of shape would 

 be very striking. In some cases both skull and beak exceed the average breadth ; in 

 others both fall short of it, and again, in others sometimes one part, sometimes the other is 

 out of proportion. 



The nasals in the Boston whale are very short in proportion to their width, and perhaps 

 are rather smaller than usual. The shape of the supra-occipital is different in all the plates 

 lately referred to ; in this specimen, however, it has the narrowness above and the breadth 

 below, which Van Beneden considers a specific character. The supra-orbital plates are 

 remarkable, inasmuch as the inner border is decidedly shorter than usual, thus making the 

 anterior edge less oblique. 



The variation in the degree of ossification of the rings of the cervical vertebrae is so gener- 

 ally admitted as to require no comment, unless it be that the non-union in the third is re- 

 markal)le. The cervical vertebrse are interesting, as in connection with those other speci- 

 mens they are fatal to the validity of one of the characteristics of the species P. Duguidii, 

 The atlas and axis resemble respectively Gray's figures for the P. Duguidii rather than those 

 of the P. antiquorum. Mr. Murie states that the atlas of the Rosherville Whale approaches 

 that of the former, but the axis that of the latter. 



Mr. Heddle, in his paper on the Laman and Copinshay whales,^ subsequently the P. Du- 

 guidii, states that in them the transverse processes fall somewhat from the plane of the body, 

 while in the P. antiquorum they rise ; a little study shows, however, that the difference is 

 usually by no means so great as represented in his diagrams. The fifth cervical of the 

 Rosherville Whale is more like that of the P. Duguidii ; the same bone in the Boston is 

 more like that of the P. antiquorum, Imt its body is larger in proportion. 



The most i-emarkable point about the vertebral column of this specimen is that it is 

 formed of sixty-three vertebrce, which is one more than has ever been described in this 

 species. 



The anterior ribs present a curious variation in being more developed than in the Rosh- 

 erville whale, although the latter was fully adult. 



When the large number of points in which this whale is peculiar is considered, 

 it cannot be denied that bolder feats in classification have been attempted than would 

 be requisite to found a new species on this specimen. Such a course, however, would be 

 quite unjustifiable. It is to be particularly noticed that these variations do not point in 

 any one direction ; that if in certain aspects this specimen approaches a certain other, yet 

 in others equally important, it may resemble a third which is quite unlike the second, and 

 in still other respects be different from both. A slight study of the writings of the eminent 

 observers so often quoted will be sufficient to show that the same is true, to a greater or 

 less extent, of perhaps every well described specimen of the species. 



In the course of time a greater subdivision will perhaps be warranted, but the best no- 

 menclature is one broad enough to be strengthened and not destroyed by progress. 



Before concluding I would express my sense of the kindness of my friend H. G. Curtis, 

 Esq., who made the drawings for all the figures in Plate vi, and all those in the text, except 

 1 and 2, by Mr. Blake, and 10 and 11. 



'Proceedings Zoological Society, London, 1856, p. 187. 



aLEMOIRS BOST. POO. NAT. HIST. VOL. II. 58 



