Art. XXV.—Notes on a Skeleton of Megaptera lalandii (novæ-zealandiæ), Gray.
[Read before the Philosophical Institute of Canterbury, 6th April, 1882.]
The Canterbury Museum possesses a skeleton of this whale, caught on May 6th, 1875, in Akaroa Harbour. The animal, a female, was accompanied by her calf. This was also killed, but unfortunately I heard of it too late for recovering its skeleton. Hitherto, as far as I am aware, no complete skeleton of this species had been obtained in New Zealand, although considerable portions of it are preserved in several museums in the Colony. The New Zealand species was established by the late Dr. Gray from an earbone alone; but Dr. Hector, after having compared the skull of our Megaptera with that of the Cape of Good Hope in the Paris Museum, states that the animals belong both to the same species.* With this conclusion I fully agree, because, after comparing carefully the different parts of the Canterbury Museum specimen, with those described and figured in the Ostéographie des Cétacées by Van Beneden and Gervais, no distinctive features of sufficient importance could be found to separate the New Zealannd humpback whale from that occurring at the Cape. As the specimen under review had already been cut up before I became aware of its capture,
[Footnote] * Trans. N.Z. Inst., vol. x., p. 336.
no measurement of the animal in the flesh could be taken. Allowing for the intercartilage of the vertebræ, the animal had probably a total length of 30 feet. The skull measures 7 feet 8 inches in length, with a greatest width across the ossa zygomatica of 5 feet.
The animal was evidently a young one, all the plates of the vertebræ and the epiphyses of both extremities of the pectoral limb being still unanchylosed. I counted 318 plates of baleen on each side of the jaw.
It is short, has the usual falcate form, is of a uniform black colour, and is edged with thick bristles. Beginning at the gape it increases rapidly in size, so that the sixtieth plate is 4 ¾ inches broad at the base, and 13½ inches long, with a length of the bristles at the tip of 2 inches. This size it maintains for about 150 plates till to the hundredth plate from the snout, when it begins to diminish in size, so that at the sixtieth plate it is only 10 inches high and 3 ¾ inches broad at the base. It still continues to become gradually smaller till the twentieth plate is reached, when it rapidly decreases in size. The number of vertebræ of which the 7 cervical are all free is—7 cervical, 13 dorsal, 10 lumbar, 21 caudal: total 51. We possess, however, 19 caudal vertebræ only, the two last, and, according to my informant, very small vertebræ having been lost during the transmission of the skeleton. There are only 13 dorsal vertebræ instead of 14, as usually occurring in them, but I am certain that one pair of ribs is neither wanting nor could I find any articulation on the twenty-first or first lumbar vertebra, which in every respect resembled the following or second lumbar. Van Beneden and Gervais, on page 127 of their “Osteographie des Cétacées,” state, when speaking of the northern humpback, Megaptera boops, “II y a des squelettes à treize côtes, mais l'on peut supposer, qu'il y a une qui manque.” In view of the occurrence of a similar deficiency in the humpback of the southern hemisphere where according to the same authors the number of the dorsal vertebræ is 14, the same as in M. boops, we have to admit that the number varies between 13 and 14. The number of lumbar vertebræ is given as 9. However, I failed to find in the tenth or following vertebra, which ought to be taken as the first caudal, any sign of a hypapophysis for the articulation of the first chevron bone; it resembled in this respect entirely the foregoing ninth lumbar. The space for this articulation in the next or eleventh vertebra is marked so very slightly, that I once thought it might also be added to the lumbars. In that case there would have been 11 lumbars and 20 caudal vertebræ. Lilljeborg in his exhaustive memoir on the Scandinavian Cetacea published by the Ray Society amongst the memoirs on the Cetacea, states that Megaptera boops has 11 lumbo-sacral and 21 caudal vertebræ. He has probably experienced the same difficulty as I had to distinguish
between the last lumbar and first caudal. It may, however, be possible that the first chevron bones are so very rudimentary that they were not secured at the time, in both instances, and that moreover they do not articulate with the posterior lower surface of the vertebra in question. Van Beneden and Gervais state that the spinal processes augment in height along the vertebral column to the first lumbar vertebra in M. boops. No information is offered on this point in their description of the skeleton of M. lalandii. I found in the New Zealand specimen that the spinal processes continue rising up to the third lumbar, which is 11 ⅜ inches high, the first being 10 ¾ inches and the second 11 inches.
The sternum, a rather thickish bone, is 9 ¼ inches high and 9 inches broad. It is rounded at the top and pointed below. One well-marked articulation exists on each side for the attachment of the rib. I have added a drawing (the inner side of the bone) in illustration.
The sternum of Megaptera on pl. ix. of Van Beneden's and Gervais' work varies very much from ours, as it is more in the form of a horseshoe, with its frontal part downwards, so that the open side is at the top.
The scapula, of which a correct drawing of that of the left side also accompanies these notes, measures 29½ inches in breadth by 21½ inches in height. It does not possess the character of the scapula figured by Van Beneden and Gervais on page 133 of their previouslycited work, where a well-marked acromion is existing.
Our specimen, although not totally devoid of this character in the northern Megaptera, shows this only in a very rudimentary degree. The spot whence the acromion starts in the Balæmidœ is only very slightly swollen, so that a small curve is marked on the outline of the bone. There is no sign of a coracoid.
The drawing of the scapula on plate ix. of the atlas belonging to the same work is however more in accordance with the bone of the New Zealand specimen.