THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 241 



black and white and the amount aud distribution of these colors are variable to 

 the same extent in specimens from the eastern and western Atlantic. 



3. The measurements of external proportions of the body and fins show a 

 substantial agreement, except as regards the spread of the flukes, in which there is 

 an unexplained variability. 



4. The abdominal folds agree in number, size, and especially in arrangement. 



5. The dermal tubercles on the head agree well in number, size, and general 

 arrangement, though there is a large individual variation. 



6. There is no constant difference in the shape of the dorsal fin between the 

 American and European Humpbacks, unless it be that the tip is thicker in Green- 

 land specimens. 



V. The pectoral fin agrees in length, breadth, and especially in the protuber- 

 ances of the margins. 



8. The flukes are alike in form, with a possible difference in spread. 



9. The outline of the caudal peduncle or " small " is alike in Newfoundland and 

 Norwegian specimens. 



10. The skeleton agrees closely in the number of vertebrae and the formula for 

 the same; in the proportions of the skull and of the bones of the limbs. The 

 Greenland Humpback, however, appears from Eschricht's figure to have smaller 

 nasals than the others, and more deeply emarginated frontal orbital processes, but 

 there is a strong presumption that the figure is inaccurate. 



Considering the difficulties encountered in instituting exact comparisons be- 

 tween data recorded at different times by different observers, the agreement is 

 sufficiently close to justify the opinion that the Humpback whales of the North 

 Atlantic are all referable to the same species. In other words, the differences between 

 the nominal species M. nodosa, longimana, osphyia, bellicosa, americana, etc., are not 

 substantiated. 



Although the type-skeleton of M. osphyia Cope, which in the foregoing pages 

 has been currently treated as representing the common Humpback of the western 

 North Atlantic, shows no differences which would render such treatment unwar- 

 ranted, it seems to me desirable to consider a little further the differences by which 

 Cope supposed it could be separated from M. longimana. 



Cope compares his species with M. longimana as described in the works of 

 Rudolphi, Gray, and Flower, and concludes that it is different for the following 

 reasons : 



1. M. osphyia has long inferior lateral processes in the posterior cervical 

 vertebrae. 



2. The atlas is a parallelepiped in form, the transverse processes are elevated, 

 and there is an "internal process." 



3. The cranium is broader in proportion to its length than in M. longimana, 

 and shorter in proportion to the total length of the skeleton. 



4. The pectoral fins are shorter. 



5. The vertebrae and chevrons are less in number. 



6. The first pair of ribs is very broad. 



7. The spines of the lumbar vertebras are much higher. 



