| OCR Text |
Show 1886.] MR. R. COLLKTT ON BAL.ENOPTKRA BOREALIS. 253 of the dorsal fin. The genital opening lies almost immediately in front of the anterior edge. The Inferior Maxilla.-The length of the lower jaw-bones (measured to the angle of the mouth in the non-skeletonized animal) is, compared to the total length, as 1 to 4|, viz :- No. 2. . 4-5. No. 3. .4 5. No. 5. . 4-7. No. 6..4-4. In this last specimen the lower jaw-bones, probably on account of their weight, were displaced, which is often the case. The jaws have the same relative length as B. sibbaldi, and are longer than in the other two species. In these three species the proportions (according to Sars) are as follows :- B. sibbaldi, 4-5. B. musculus, 5*0. B. rostrata, 5-5. Their greatest breadth (measured between the eyes) is, compared to their length, as 1 to 1"7. This was somewhat less in a skeleton in the Bergen Museum (total length 3 0 ^ feet), where the breadth across the temporal bones (according to Lilljeborg) was, compared to the length of the skull, as 1 to 2*0. VII. Baleen. The colour of the baleen is usually black and the bristles white ; in some individuals, however, a small number of the foremost rows were white, or mottled with white, but not symmetrically in each ramus. Besides the baleen in the six specially examined specimens, I examined a considerable quantity of whalebone which lay heaped up on the beach at the different establishments. Amongst all this, I only found two specimens which differed from the others in having some white mottled plates; in all the others it was entirely black. Of these two individuals, one had on the right side 58, and on the left 53 of the foremost baleen-plates mottled -. The second specimen had on the right side 52 white plates, on the left only 5 '*. The number of the plates was about 330 in each jaw, in some 1 Namely in the following manner:-On the right side the foremost 27 were white in their outer half, and the next 15 quite wbite, after which came 3 grey plates. Then came 10 completely black, and finally 3 which were white with black edges. Total 58. The remainder were black. On the left side the colouring was somewhat similar. The first 31 were semi-white, and the next 9 quite white, then followed 3 blackish grey, after which came 3 white, then 2 greyish black, and finally 5 white. Total 53. The rest were black. 2 In this specimen on the left side the 5 foremost ones were wbite, all the others black ; on the right side the first 36 plates were mottled with white, after which came 16 quite white, the remainder being black. |
