FIGURES 57 to 66. Sternum of Balaenoptera acuto-rostrata.. FIGURE 67. Pectoral Fin of Balaenoptera acuto-rostrata from Greenland... 205 209 FIGURES 94 to 96. Skeleton of Balanoptera velifera (?), in the Wistar Institute, Philadelphia.. 281 282 For Explanation of Plates 1 to 50, see page 311. THE WHALEBONE WHALES OF THE WEST ERN NORTH ATLANTIC, COMPARED BY FREDERICK W. TRUE, HEAD CURATOR, DEPARTMENT OF BIOLOGY, U. S. NATIONAL MUSEUM. INTRODUCTION. Several years ago I began a study of the species of whalebone whales which frequent the western North Atlantic, with a view of ascertaining the facts regarding their distribution and migrations. I was confronted at once by the uncertainty in the nomenclature of the species frequenting European waters, with which the American forms were known to be closely allied, and my first undertaking was to ascertain the identity of the species described by Linnæus in the tenth edition of the Systema Naturæ. The results of this search for correct scientific names were published in 1898.1 Having fixed the names of the European species as far as possible, I next endeavored to locate the material on which the American species described by Cope and other cetologists had been based, and began a comparison of these types and of such other material as existed in the National Museum and other similar establishments in the United States with the European forms. For a considerable time I was so situated as to be unable to work on specimens, and during this period I collected from every available source records of the occurrence of whalebone whales on the Atlantic coast of North America, beginning with the very On the nomenclature of the whalebone whales of the tenth edition of Linnæus's Systema Naturæ. Proc. U. S. Nat. Mus., 21, 1898, pp. 617-635, No. 1163. earliest literature relating to the continent. It seemed probable that the investigation of the species themselves and of the records of their distribution could be carried on together and the results in both directions made ready for publication in one work. In this I have been disappointed. The work on the species has occupied a much longer time than was anticipated, and has made it necessary to defer the intimate study of the records of geographical distribution. It has seemed to me desirable, however, to publish with the discussion of the species a summary of the distribution records, so that in case the work originally projected cannot be completed by myself, the time of any subsequent investigator in this field may be economized. It happened very opportunely while the study of the American species was in progress that a fishery for Finbacks and Humpbacks, similar to that carried on in Norway for many years, was established in Newfoundland. With the permission of the Secretary of the Smithsonian Institution I visited this fishery twice, and enjoyed the extraordinary facilities there afforded for the examination of fresh specimens of three species of baleen whales. No similar opportunity has, I believe, been open to American naturalists in the past. Not only could the matter of species be investigated under favorable conditions, but a good opportunity was afforded for the study of individual variation among these huge animals, whereby the probabilities as to the validity of sundry nominal species could be satisfactorily estimated. The plates published herewith contain many photographic figures of different individuals of the same species, showing the extent of variation in color, form, etc. So far as I am aware, no similar figures from photographs have been published heretofore. As nearly every cetologist takes occasion to say, the investigation of animals so large as whales is surrounded with peculiar difficulties. The physical labor involved in examining and turning about the massive bones and other parts is very fatiguing, and the mere weight of the specimens often thwarts the investigator. In museums whale skeletons are commonly suspended from the roof so as to be practically inaccessible without the use of ladders and other unwieldy appli ances, or the bones are stored in dark and dusty corners where they can be studied only with much begriming of note-books, hands, and clothes. The size of the whalebone whales, the large expense involved in preparing specimens for scientific purposes, and the large amount of space such specimens occupy, render it improbable that extensive series of specimens will ever be assembled as is the practice nowadays with small mammals. Even if skeletons and casts were so assembled, they could not be compared one with another without the greatest difficulty. It follows that the methods of comparison which are employed advantageously in the case of small species can hardly be used here. Reliance must be placed instead on notes and photographs. So far as the exterior is concerned, there is a certain compensating advantage no doubt in the direct study of fresh specimens rather than of skins artificially prepared, though this applies only where conditions are at least approximately as good as they are at the Newfoundland stations. Many of the errors with which cetology is encumbered are due to the observation of stranded specimens in various stages of decomposition, in which the natural appearance and relationships of parts were partially or entirely obscured. Perhaps the greatest difficulty with which systematic cetology has to deal is the problem of individual variation. The extent to which individuals of the same species vary is enormous, and one unacquainted with this fact would be disposed to multiply species liberally, only to find after more extensive comparisons that the characters were slipping away. On account of the extraordinary individual variation in this group of mammals, and the peculiar character of the material, it would seem the part of wisdom to treat the matter of species conservatively. To a certain extent the absence of definite barriers in the ocean permits the whales to range more widely than is usual with land mammals, and on this account geographical races or sub-species are less likely to be formed. Still, from the observations of Scammon and others, it seems probable that species may in some cases be repre sented in the ocean by distinct herds, which are distinguishable by various peculiarities of size, form, proportion, and color. It is not certain, however, that these peculiarities may not be due to difference in sex and age. In the study of these animals, the question obtrudes itself whether groups of individuals belonging to certain species when separated from the remainder of the species by the width of a continent, can and do continue to reproduce their kind for an indefinite period without change. To decide the question negatively on a priori grounds, as is the tendency to-day, is, I think, unscientific. The present investigation, in so far as it reaches such questions, appears to support the view that detached groups of individuals of a species can perpetuate the characters of the species to which they belong for an indefinite period. To find a difference and erect upon it a species, is far easier than to prove that this difference is merely an individual variation or age distinction. Furthermore, species once established, though based on very unsubstantial characters, often acquire a standing which no amount of criticism can affect. Such “species,” it would seem, should have another name and be placed in a separate category. On the other hand, reluctance to accept species because they add to the length of the list, or to reduce them to synonymy without an examination of the material on which they are based, is to be decried. Between these two erroneous courses I have endeavored to steer in the present work. I appreciate that the conclusions arrived at here are little more than a confirmation of opinions held by Van Beneden and some other masters of cetology, but with few exceptions these opinions regarding American whales were not based on the examination of American material. If I am not deceived, they proceeded rather from the a priori conclusion that it was not probable that other species existed than those frequenting European waters. With the exception of the type of Balana cisarctica, the types of the American species of Cope and Scammon are figured here from photographs for the first time. Cope intended to monograph his species, but never brought the work to completion. |