84 THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



Upon reducing the foregoing measurements to percentages of the total length, 

 we find that the distance from the end of the snout to the axilla is 34.3 %. In 

 Newfoundland specimens of the " Common Finback," which is closely allied to or 

 identical with Balcenoptera physalus, as will be seen later, the average for this 

 distance is 33.2 % of the total length. The length of the pectoral (presumably 

 from the axilla) is 9.1$. In nine Newfoundland specimens of the Common Fin- 

 back the average is 8.3 %. The breadth of the pectoral is 2.7$ as against 2.9$ in 

 Newfoundland specimens. 



The color of 8. tuberosus is given in the original description as "jet black 

 above, white on the belly ; sides beautifully marbled by the combination of the 

 two colors." In the story in the American Field, however, the color is thus 

 described (see p. 83): "There was a line of demarkation down his side where the 

 gleaming white of his belly joined his marbled, grayish black back." The latter 

 description was, of course, from the fresh specimen while the former was probably 

 from the dead whale. It is a well-known fact that the gray color in cetaceans 

 changes very rapidly after death to black. Taking either description, there is no 

 reason for considering 8. tuberosus to be other than the Common Finback of North 

 American waters. 



Considering the external characters and proportions as a whole, it seems prob- 

 able that the Mobjack Bay specimen was a Common Finback, which is the American 

 representative of, or identical with, Balcenoptera physalus (L.). 



There is only one other well-known North Atlantic Finback with which the 

 Mobjack Bay specimen can be associated. This is B. borealis. In this species, 

 however, the dorsal fin is situated well forward, the pectoral fins are unusually 

 small, and the amount of white on the belly is much restricted. None of these 

 characters was present in the Mobjack Bay specimen, as far as can be ascertained 

 from the published accounts. 



The question of the identity of 8. tuberosus cannot be positively decided until 

 some of the more important bones of the Mobjack Bay specimen are found and 

 examined. In the present article I shall consider it as belonging to the American 

 form of B. physalus (L.). 



In order to present the matter fully and fairly, I would add the following: If 

 all that Cope stated regarding the skeleton which he described in 1866 is taken 

 as really applying to the Mobjack specimen, and all that was added to the original 

 description of the exterior in the later papers is interpreted favorably, quite a 

 strong case can be made out for identifying 8. tuberosus with B. borealis, or at least 

 associating it with that species. Thus, while the color of the baleen is not given in 

 the original description, in the article of 1866 it is said to be black, which would 

 indicate an ally of B. borealis, and exclude B. physalus (L.). In the same 

 article, the type of 8. tuberosus is stated to be "entirely adult at a length of 

 43 feet (axial)," which would exclude both B. musculus (L.) and B. physalus 

 (L.), but admit B. borealis. Again, in the description of the skeleton, it is stated 

 that "the 2*?, 3?, and 4*. h cervicals are with large completely united superior 

 and inferior lateral processes." This would confirm the statement that the speci- 



