THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 207 
very probable, but on account of the great amount of individual variation among 
cetaceans it would be an almost hopeless task to recognize and characterize them 
without a wealth of material which no museum in the world possesses to-day. 
To bring together a hundred or a thousand specimens of mice or sparrows side by 
side for comparison is an easy task, but to accomplish the same for the huge whale- 
bone whales is almost beyond the bounds of possibility. To say nothing of me- 
chanical difficulties, the expense involved would be prohibitive. 
The most that the cetologist can hope to do is by collating notes upon, and 
measurements, photographs, and drawings of, such specimens as can be found at the 
whaling stations and in museums, to detect constant differences of considerable 
magnitude. These differences will form the basis of his species. Beyond this he 
can scarcely go, with any feeling of certainty. 
The importance of the bearing of these considerations on the questions of 
geographical distribution cannot be ignored, and it may be thought that they impair 
the usefulness of the present inquiry, for it is a well-known fact that among 
migratory species groups of individuals presenting but slight differences may follow 
quite different routes of migration and occupy quite widely separated stations. 
There is no doubt much force in criticism along this line, and it should put the 
cetologist on his guard against relying too implicitly upon the results of the rather 
erude methods which alone are open to him in systematic work. Nevertheless, 
conclusions as to geographical distribution based on such results, carefully worked 
out, must certainly have more value than opinions formed on @ préort grounds, with- 
out actual examination of specimens, of which cetology has not been free in times 
past. Furthermore, examination of even a small number of specimens may lead to 
the detection of large differences, and so put the question of close relationship out 
of court. 
The differences between the Greenland and Norwegian skeletons of B. acuto- 
rostrata which Eschricht finally thought might be of importance were as fol- 
lows: (1) A slight difference in the position of the dorsal fin, amounting to 75 the 
total length, as shown in a sketch received by him; (2) union of the lateral 
processes of the 5th and 6th cervical vertebree in the immature skeletons from 
Greenland, a condition not found by him in Norwegian specimens of more 
advanced age; (8) the coronoid process of the mandible “higher, smaller, and 
more strongly bent outward” in the Greenland skeletons; and (4) absence of 
obliquity of the upper jaw in the latter. 
As to the first point, the position of the dorsal fin, it may be said that a 
variation of 7. of the total length, amounting actually in the case of the Greenland 
specimen to about 4 inches, is not greater than is found in other species of Balenop- 
tera. In this particular case, however, it is quite as likely that the sketch was 
slightly inaccurate, as that the variation actually existed. At all events, no stress 
ean be laid on this point under the circumstances. 
The second point brought forward by Eschricht as possibly serving to dis- 
tinguish the Greenland species was that the specimens though immature and only 
about 17 or 18 feet long, had the processes of the 5th and 6th cervicals united, 
