132 THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



that his specimen represented B. laticeps Gray, a synonym of B. borealis Lesson, 

 but it is in reality B. physahis, as is indicated by the number of vertebrae, color of 

 body, color of whalebone, etc. 



It must be admitted that the correspondence between Menge's figures and those 

 of American specimens on pis. 1-4 is very close. The skull appears to differ less 

 from the American specimens than they do from one another, except in one par- 

 ticular. The width of the vertex appears to be less in Menge's photograph than in 

 the American specimens, and the proximal end of the nasal process of the maxilla 

 narrower. This same feature is to be observed in the figures of Eschricht and 

 of Van Beneden and Gervais, and may constitute a real difference between the 

 American and European skulls. It is to be noted, however, that Dwight's figure 

 of the Gloucester, Mass., skull has the vertex and maxilla even narrower than 

 Menge's photograph, but this figure is not correct as regards the intertnaxillse and 

 may be otherwise inaccurate. 



In Sars's figure of an European skull, the width of the vertex is as great as in 

 the American specimens, and the occipital border is straight as in the Rochester 

 (New York) specimen. In the type of B. tectirostris (Cope), the margin of the 

 supraoccipital is convex forward at the vertex (pi. 1, fig. 1). The breadth of the 

 vertex is 13 inches. 



As already mentioned, the American skulls differ very considerably among 

 themselves. It will be noted, for example, that the Cape Cod specimen, No. 16039, 

 IT. S. N. M., agrees with the type of B. tectirost/ris (Cope) in having very sharp- 

 pointed nasals (pi. 1, fig. 3), while the Cape Cod skull, No. 16045, U. S. N. M., agrees 

 with the Rochester (New York) skull in having blunt nasals. (Compare pi. 1, fig. 

 2 and pi. 3, fig. 1.) The form of these bones in No. 16045 is precisely that given 

 by Flower for an European specimen in the Royal College of Surgeons, London 

 (P. Z. 8., 1864, p. 390, fig. 4). This Rochester skull is peculiar in having the antero- 

 superior margin of the occipital quite square, while in the other skulls the margin 

 is more or less semicircular. It is a mature specimen, while the others are immature. 



The proportions of the skulls, as indicated by comparative measurements, would 

 constitute an excellent criterion of likeness or unlikeness. Unfortunately, detailed 

 measurements of skulls of European specimens have been published in but a few 

 instances, and these are not always comparable. In the first table on page 133 

 a number of such measurements, reduced to percentages of the total length, for both 

 European and American specimens, are brought together. 



As the American specimens at command are all immature, it is necessary in 

 instituting comparisons to exclude all the mature European specimens. Unfortu- 

 nately, this leaves but one European specimen, that stranded at Nairn, Scotland, and 

 reported by Prof. Struthers (88, 330). As Struthers's measurements can, however, 

 be thoroughly relied upon, and as all of the American specimens except one were 

 measured by a single observer (myself), this comparison may be regarded as of more 

 value than would ordinarily be the case. The average percentages for the 

 American specimens, including the type of B. tectirostris (Cope), and the percentages 

 for the Nairn specimen are as indicated in the second table on page 133. 



