Imágenes de páginas
PDF
EPUB

The phalanges are incomplete in the type of M. osphyia. They are arranged on each pectoral in three series, or digits, each digit having 3 phalanges, exclusive of the metacarpals. Each limb, therefore, has but 9 phalanges in all, showing that many are lacking. Some of the pieces mounted as metacarpals are probably phalanges.

The number of phalanges in the type of M. bellicosa is not given by Cope, and I was unable to find any considerable number of these bones, when examining the skeleton in the Philadelphia museum. Cope remarks that “the fore limbs are neither of them quite complete.” (29.)

In the immature skeleton in the National Museum from Provincetown, Mass., (No. 16252 4) the formula for the left side is 2, 6, 6, 2.' In No. 21492, U. S. N. M., also from Cape Cod, Mass., the formula is 2, 7, 6, 1, as now mounted.

From the emarginations and tubercles on the anterior border of the pectorals in the Newfoundland specimens (pls. 37-40), both adult and fætal, and in the

FIG. 79

Fig. 8o.

Fig. 81.

FIG. 82.

Fig. 83.

MEGAPTERA NODOSA (BONNATERRE). AMERICAN AND EUROPEAN. STERNUM.
Fig. 79.-ST. BARTHOLOMEW ID., WEST INDIES. (From MALM.) Fig. 80.—(From VAN BENEDEN.
ITY NOT GIVEN.) Fig. 81.-TAY RIVER, SCOTLAND. Ô. (FROM STRUTHERS.) Fig. 82.-ANTILLES.
Fischer.) Fig. 83.—TYPE OF M. LONGIMANA. (From PANDER AND D'ALTON.)

LOCAL(FROM

Cape Cod (Mass.) specimen (pl. 41, fig. 6), it is certain that the same number of phalanges may be counted for digit 2 in these specimens as in the Greenland Humpback and the European species, and for digit 3 the variation can hardly be more than one phalanx, with a probability that there is no difference.

1

On the right side, the formula is actually 2, 5, 5, 2, but one phalanx has obviously been lost from digits 3 and 4, as the irons supporting the bones project a considerable distance beyond the last phalanges now in position. Mr. F. A. Lucas has kindly given the formula for the fresh specimen, as recorded by him at the time it originally passed through his hands. It is the same as above, viz., 2, 6, 6, 2.

The phalanges on digits 4 and 5 cannot, of course, be estimated in the same way, as they are not indicated on the posterior margin of the fin.

STERNUM.

The sternum has not been preserved in the American skeletons with which I am familiar. Fischer (44) has figured the sternum of a specimen from the Antilles, which should represent Cope's M. bellicosa, and Malm (66, pl. 1, fig. 4b) has also given a figure of a partially incomplete sternum from St. Bartholomew Island. These, with the sterna of two European specimens, are represented in the outlines (text figs. 79 to 83) on p. 239. They show that there is no essential difference in the pattern of the sternum in the American and European Humpbacks. From a systematic point of view the sternum is of little importance, on account of the large amount of individual variation to which it is subject.

RIBS.

The first rib in Megaptera is broad at the distal end. In the type of M. bellicosa it is cut off square (pl. 35, fig. 2), but in the Tay River whale, according to Struthers's description and figure, the distal end is emarginated, more strongly on the right side than on the left, forming an anterior and posterior angle.

The second rib in M. bellicosa has an oblong prolongation at the proximal end, with parallel margins, from the head to the angle. The second rib in the series of ribs from St. Bartholomew Island figured by Malm (66, pl. 1, fig. 4c) is club-like at the proximal end, without distinct processes, while the second rib in the Tay River whale “has a prominent tubercle, the end sloping obliquely downward and inward, giving a broad triangular beak.” This is seen in the third rib of the type of M. bellicosa, but not in the second. In the Humpback described by Van Beneden and Gervais “the third, especially, and the fourth differ from the others by possessing a distinct head” (8).

It will be seen that no two skeletons agree in the shape of the ribs, and these parts therefore do not aid in the discrimination of species.

SUMMARY.

From the foregoing presentation of the recorded data relative to the external and osteological characters of the Humpbacks of the coast of Europe, Greenland, and the North American mainland, the following condensed statement may

be drawn up:

1. The average and maximum lengths for the Humpbacks taken at the Finmark wbaling stations, according to Cocks's measurements, are larger than the measurements of those taken at Newfoundland. On the other hand, Humpbacks from Bermuda and Greenland are cited as larger than the Finmark specimens.

2. The Humpbacks of both sides of the Atlantic have the same two colors

black and white—and the amount and 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 Greenland specimens.

7. 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 vertebræ 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 between 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 unwarranted, 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 bas long inferior lateral processes in the posterior cervical vertebræe.

2. The atlas is a parallelopiped 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 vertebræ and chevrons are less in number.
6. The first pair of ribs is very

broad.
7. The spines of the lumbar vertebræ are much bigher.

I have already shown that the 4th and 7th characters are fictitious, as advanced by Cope, and that the 1st is merely an individual variation.

The width of the cranium of the type of M. osphyia (3d character) as compared with the length, differs from that in the Scotch skulls carefully measured by Struthers by only 1.1 per cent., which in actual measurement amounts to only 1} inches. This is certainly not significant, and is within the limit of variation of different American specimens of the Humpback among themselves.

The number of vertebræ (5th character) in the type-skeleton as mounted is 48, probably to be distributed as follows: C. 7, D. 14, L. 10, Ca. 17 (+) = (48 +). The last vertebra present is 4 in. square, and according to Struthers's measurements of M. longimana, about 4 more caudals must have been present originally, making 52 for the whole column, which is the average for M. longimana. Of chevrons there are 7 in position in the type of M. osphyia, with places for perhaps 10 in all. Van Beneden and Gervais give 12 as the number for M. longimana, but it is to be remarked that Struthers's Tay River (Scotland) specimen had but 10 chevrons, and the skeleton in the National Museum (No. 16252) from Cape Cod, Mass., but 9, so that it would appear that the number is variable, and unreliable as a specific character.

In the type of M. osphyia the breadth of the first rib on the left side is 9 iv., and on the right 74 in. In Struthers's Tay River specimen the right rib of the first pair has a maximum breadth of 8.6 in., and the left, 5.3 in. It is obvious that the breadth is so variable even on the two sides of the same skeleton that it is useless as a specific character, but in this instance, as the skull of Struthers's specimen is but 125 in. long, while that of M. osphyia is 135 in. long, the maximum breadth of the first ribs in the two skeletons is practically the same relatively, with a little increase in favor of the European specimens.

In 1868 Cope cited as an additional character of M. osphyia the contraction of the orbital process of the frontal at the distal extremity (27, 194). He remarks : “The orbital processes of the frontal bone are not contracted at the extremities as in M. longimana, but are more as in Balanopteræ; entire width over and within edge of orbit, 15} in.” This measurement I make 14 in. instead of 15į in. The former equals 10.4 % of the length of the skull. As shown in the table on p. 233, the same measurement from Rudolphi's figure of the type of M. longimana is 9.0 %, and of Struthers's Tay River specimen 9.6 %, while the type of M. bellicosa gives 10.7 %. This approximation shows that M. osphyia presents no great deviation in the breadth of the supraorbital edge of the frontal. "It is true that in Rudolphi's figure of the whole skeleton of the type of M. longimana the orbit itself appears smaller, but in a general figure of this kind the proportions of the smaller parts are frequently inaccurate. The least longitudinal diameter of the orbit in Struthers's Tay River whale is, according to his measurements, the same as in the types of M. osphyia and M. bellicosa. As it is extremely unlikely that the two European skeletons belong to different species, the probability that Rudolphi's figure is inaccurate as regards the orbit is strengthened by this circumstance.

The Humpback appears to have been known to European zoologists only from

American sources, until the time of Rudolphi's description of M. longimana in 1832. This author suspected that his species might be the same as Fabricius's boöps, and Schlegel in 1844 was of the same opinion.

In 1848 Eschricht arrived at the same conclusion from an opposite point of view, and in 1819 stated emphatically: “ It is now raised beyond all doubt that the whale stranded in the mouth of the Elbe River in 1824, and described by Rudolphi as Balæna longimana, is nothing more and nothing less than an individual of the commonest species of baleen whale on the Greenland coast, known to the Greenlanders as the Keporkak ; also mentioned by Anderson under the latter name and introduced into systematic zoology by Klein and Bonnaterre under the appropriate name Balana nodosa(37, 57). As this latter name is derived from the description of the New England Humpback, Eschricht combines not only the Greenland and European Humpbacks but those of the coast of the United States as well, in one species. Gray, however, was not content to have it so, and already, in 1846, separated the “Bermuda Humpback" under the name of Megaptera americana (56). In 1866 he still adhered to this arrangement, employing the name M. americana as before and citing Fabricius's Balena boöps with a mark of interrogation, under M. longimana, with the comment: “Rudolphi, and after him Schlegel, refer B. boöps, 0. Fabricius, to this species; and Professor Eschricht has no doubt that Balæna boöps of O. Fabricius is intended for this species, as it is called Keporkak by the Greenlanders. If this be the case, Fabricius's description of the form and position of the dorsal fin and the position of the sexual organs is not correct” (53, 124), Gray seems not to have known at this time of Cope's description of M. osphyia, published in 1865. In the supplement to his catalogue he quotes Cope's description, but without comment.

In 1869, Van Beneden and Gervais remark as regards osphyia and boöps (= longimana): “We do not find any difference of value for separating them ” (8, 236). and again in 1889 Van Beneden unites all the American Humpbacks in one species.

Fischer (44, 58), who studied the Humpback bones from Martinique Id. in the Bordeaux museum, which should presumably represent M. bellicosa, was unable to decide whether they should be assigned to the same species as the Greenland Humpback, and closes his investigation with the inquiry whether all the Humpbacks should not be regarded as belonging to a single species.

Note.—Two excellent illustrations of the Newfoundland Humpback, from negatives obtained by Mr. Wm. Palmer, of the U. S. National Museum, in 1903, are reproduced on plate 38, figs. 1 and 2. The individual represented in fig. 1 is unusually white and on that account especially interesting.

« AnteriorContinuar »