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PUBLIC RECORD OFFICE

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CO. 885

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23 PUBLIC RECORD OFFICE, LONDON

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APPENDICES.

it is stated that sperm whales, black humpbacked whales, and blue whales are found of the west coast; and that :-

"of these by far the greatest number are the humpbacked whales, and these come up from the south polar seas, on their way to the Bay of Biafra, where they breed each year.

*

They are on their northward run from May till the end of July, and on their return journey from the middle of August until the middle of November.

"They usually follow the line of the coast, and do not go more than about twelve miles out.'

An important point may be noticed here in passing. Lieutenant Strong speaks of "black humpbacked whales," and this description of them was, no doubt, given to him by the whalers; if so, then it probably refers to the coloration of the under- parts. It may be suggested, therefore, that the black-bellied race is the one of the three races found at South Georgia which migrates to the west coast of Africa. Goodall (as quoted above under "Colour") tells us that at Durban all the humpbacks were of the marble-bellied variety, and, therefore, it may be that the marble-bellied race of South Georgia is the one which regularly migrates to the east coast of Africa. The white-bellied race does not appear to have been recognized yet away from South Georgia and South Shetland; perhaps this will be found to be the form which migrates along the eastern coast of South America in the cold Falkland current.

Summing up, there can be little doubt that the humpbacks of the South Atlantic northwards to warmer seas, and make in each year a great "breeding-migration that, after the birth of the young in the tropics, this is followed by the "feeding- migration" or return to the Antarctic regions. The time occupied by these migra- tions is considerably longer than that which the corresponding journeys of the northern humpbacks take. The southern humpbacks leave the polar sea in the autumn, pass the winter in the tropics, and return to the south in the spring; the northern humpbacks leave the polar sea in early spring, and are back again before summer is far advanced.

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It is probable that the warm equatorial currents which flow southwards along the eastern coasts of Africa and tropical and sub-tropical South America hinder the advance of the humpbacks towards the Equator when they are on their breeding- migration along those coasts; they meet with the genial conditions which they appear to desire for parturition in relatively high latitudes.

On the west coast of Africa, doubtless because of the cold northward flowing Benguela current, the southern humpbacks regularly cross the Equator on their "breeding-migration" in the months of June and July. It is a well-known fact, mentioned by Collett and Risting, that, although the majority of the humpbacks in the North Atlantic migrate regularly, in many localities, for a considerable time after the departure of the majority, individuals or even small "schools" may be found lingering behind. Should some of the southern humpbacks chance to wander a little farther than usual into the Tropic of Cancer, and should they chance to meet with a lingering "school" of northern humpbacks, they may occasionally proceed northwards with the latter on the feeding-migration" instead of returning to the south with the majority of their fellows. To the extent, therefore, that the southern herds may occasionally give individuals to the northern stock we may speak of a possible inter- Cer- change between the northern and southern races in the equatorial regions. tain facts noticed in the following paragraphs can be explained on this hypothesis, and may be taken as some evidence that such a limited interchange does actually occur sometimes. On the other hand there does not appear to be any evidence what- ever of northern humpbacks straying into the South Atlantic.

LE

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In 1871 Cope's description of his "Megaptera bellicosa was published. This species" was founded upon the skeleton of an individual 32 'ft. long, obtained by Dr. Goes in the West Indies, either off Santo Domingo, Haiti, or at St. Bartholomew Island. Among the characters which Cope found he mentions that the head "bears a greater proportion to the length of the body" in bellicosa than in M. longimana (nodosa), and he states that he was informed that the pectoral fin was black exter- nally instead of being "entirely white as in Arctic Megaptera." Although exter- nally black flippers are not unknown in northern humpbacks they are not, as noticed above under "Colour," normal occurrences. In the two points mentioned, there- fore, "M. bellicosa" may be said, judging from the facts collected by Major Barrett-Hamilton in South Georgia, to agree with the southern races rather than

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with the northern form. True re-examined the type skeleton of "H. bellicosa" and wrote an admirable criticism of Cope's description, in which he concluded that he was "justified in treating 'M. bellicosa' as representing the common humpback and not as a distinct species"; this conclusion may, of course, be quite sound without invalidating the claims of the racial or sub-specific differences which I am inclined to think exist between the northern and the southern humpbacks Cope stated that the orbital plates of the frontal are less concave anteriorly in bellicosa than in longimana (nodosa); this is admitted by True, who says that the skull "hence offers a contrast to other Megaptera skulls which I have examined, in all of which the margin is quite concave." He adds:" That this is not likely to be of importance seems probable from the fact that a further comparison of the type with specimens fails of the common humpback of the Atlantic coast of North America

to disclose correlated distinguishing characters, while the agreement extends to many parts not mentioned by Cope." It is to be hoped that some skull material of each of the three local races will be procured from South Georgia, and that this material when forthcoming will throw light on this interesting matter.

A humpback caught off the coast of Iceland in 1867, and described by Hallas. is remarkable for the great relative length of the distance between the tip of the snout and the blowhole; as has been mentioned above, this character suggests that the specimen in question may have been a wanderer from the South Atlantic.

Some small foetuses (discussed below) found in humpbacks at Finmark in March, i.e., at a time when in the north the foetus is normally nearing the period of birth, agree in size with those which are found during the same month in the southern herds, and so lend support to the view that individuals occasionally stray from the south to the north.

The following note by Mr. Haldane (Ann. Scott. Nat. Hist., 1908) is of interest in this connexion :--

"Mr. Salvesen received from Captain Bull a harpoon found in the blubber of a Megaptera killed off Iceland. It is a curious thing, 10 in. long, composed of a round rod with a loose harpoon-head into which one end of the rod fits. On the other end of the rod are two india-rubber rings, and the place where a third has been. It most likely has a South American origin, and shows what great distances these whales travel."

SEXUAL Maturity.

In the North Atlantic no female of less length than 45 ft. appears to have been found to be gravid. At South Georgia a marble-bellied female 42 ft. long (No: 04) contained a foetus 11 in. long; while a black-bellied female 43.75 ft. long was appar- ently not yet impregnated. New-born calves are estimated to be about 15 ft. long in the northern race; Mörch was informed of new-born calves at South Georgia of about 12 ft. in length. Looking at these facts together it seems possible that sexual maturity may be attained rather sooner (taking length as a standard of age) in the southern than in the northern humpbacks. In the southern race (and probably in the northern form also) sexual maturity is attained long before the fusion of the vertebral epiphyses; the latter do not fuse before the southern female is 45 ft. long, and the fusion may not be complete when her length is 495 ft.; complete fusion is, perhaps, to be regarded as a sign of middle age, if not of senility. Males are smaller than females, and there is probably no great error in assuming 37 or 38 ft. as being the minimum length of a sexually mature male of the southern races of the humpback.

Since the humpbacks of both the North and South Atlantic have a regular season for parturition, as witnessed by their annual "breeding-migration" to sub-tropical or tropical waters, we might infer that there is also a regular season for their pair- ing. A further inference might be made, namely, that in each race, at whatever time of the year it falls, the pairing season must be nearly equal in duration to the season of parturition.

To the late Professor Gustav Guldberg* is due the credit of the first attempt to utilize the data collected from the foetuses for the purpose of determining the

* Gustav A. Guldberg "Bidrag til Cetaceernes Biologi. Om forplantningen og drægtighedstiden hos de nordatlantiske Bardehvaler."-Christiania; Videnskabs-Selskabs Forhandlinger, 1886, No. 9.