THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 273 



described, and eveu in the same school or ' gam.' Moreover, we have experienced 

 the greatest difficulty in finding any two of these strange animals externally alike, 

 or possessing any marked generic or specific differences. If the differences pointed 

 out as constituting different species are maintained, we conclude there must be a 

 great number. We have observed, both in the dead and living animals, the follow- 

 ing different external marks: 1st. Body black above, white beneath. 2d. Body 

 black above and below, with more or less white mottling under the throat and above 

 the abdomen ; pectoral and caudal fins white beneath, or slightly spotted with black. 

 3d. Body black above, white beneath, with underside of pectoral and caudal fins of 

 a dark ash-color. 4th. Body black above, with gray mottling beneath. In all of 

 these varieties, both the caudal and pectoral fins differ in shape and size ; the latter 

 in some individuals being exceedingly long, narrow, and pointed, while others are 

 comparatively short and broad, as shown in the outline (page 47), which also shows 

 the parasites, commonly called barnacles, adhering to the throat, pectorals, and 

 caudal fin. There are still others whose pectorals are of intermediate proportions, 

 but terminate abruptly, as seen on page 48, which also represents the scalloped 

 flukes present in some of the individuals. Again, in other examples, the caudal fin 

 is narrow, pointed, and lunate ; in others, still, it is broad, and nearly straight on 

 the posterior edge. All these varieties feed and associate together on the same 

 ground, and in every particular their habits are the same, so far as we have been 

 able to ascertain from careful observation ; all, likewise, are infested by the same 

 parasites. As to the dorsal protuberance called the hump, it is, as has been 

 previously stated, of no regular shape or size, but is nearly of a uniform height; 

 the posterior edge is sometimes tipped with white. As to the tubercles on the 

 head and lips, they were present on all we have examined, twenty or more speci- 

 mens ; those about the head are always well-developed, while those upon the lips, 

 in many individuals, are scarcely perceptible. In some instances, however, they 

 equal or exceed those which crown the skull. There is no regularity in the number 

 of gular folds, which, as far as observed, vary in number from eighteen to twenty- 

 six. In some cases they run parallel to each other ; but usually there are several 

 that either cross or terminate near the pectorals. The animals are all described as 

 being black above ; but in the examples which have been examined, there was not 

 one when closely scrutinized, which did not reveal some light marks of white." 

 (82, 43, 44, foot-note.) 



It will be seen that the range of color variation is about the same in the 

 Pacific Humpback, as in the Atlantic species. The pectorals are perhaps more fre- 

 quently black externally, but as they are also pure white at times, as shown by 

 the photographs above-mentioned, this can hardly be looked upon as indicating 

 a specific difference. (See pi. 41, figs. 1, 2.) 



The number of abdominal ridges is not different from that found in M. 

 nodosa. 



One peculiarity merits attention. Scammon states that some parts of the body 

 in the Pacific Humpback are occasionally gray. The Newfoundland Humpbacks 

 which I examined were all black and white, without gradation or intermingling so 

 as to produce shades of gray, but Rawitz (74) has stated that one of the Humpbacks 

 examined by him at Bear Id., Norway, was gray on the throat. 



Scammon gives measurements of the three specimens above mentioned, which, 

 together with a part of the earlier ones, are as follows : 



