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Show 1886.] MR. R. COLLETT ON BALAENOPTERA BOREALIS. 265 as a rule a little in advance of the last third of the body. Vent placed exactly under hindermost edge of the dorsal fin. Flippers unusually small, measuring about ^ of the total length of the body. Baleen black ; the bristles fine, white, and curling. The number of plates about 330 ; their greatest length 650 millim.; not including the bristles. Jaws long, being to the total length about as 1 to 4|. Balamoptera musculus, Comp. 1828. Norwegian Finhval (" Finner Whale ").-Length 60 to 65 feet, seldom exceeding 70 feet. Form of the body very elongate ; the greatest height is to the total length as 1 to 6£ or 6§. Colour greyish slate above, also the left lower jaw ; the whole underside, the right lower jaw, the inner side of the flippers, and the underside of the flukes white. Dorsal fin rather low, with almost straight margins; it is placed somewhat forward, or very slightly in front of the last fourth of the body. Vent placed just beneath the anterior edge of the dorsal fin. Flippers rather small, measuring about ^ of the total length of the body. Baleen with the bristles dark bluish black or slate-colour ; on the right side, the first rows are white or whitish. The number of the plates between 350 and 370 ; their greatest length about 950 millim., not including the bristles. Jaws of moderate length, being to the total length as 1 to 5. Balamoptera sibbaldi, Gray, 1847. Norwegian Blaahval ("Blue Whale").-Length about 70 to 80 feet, seldom exceeding 85 feet. Form of the body more robust than the last species, the greatest height is to the total length as 1 to 5|. Colour dark bluish grey, with small whitish spots on the breast; the lower edge of the flippers and their inner sides white. Dorsal fin particularly low and small, with straight margins ; it is placed far back, close to the commencement of the last quarter of the body. Vent placed in front of the vertical line from the anterior edge of the dorsal fin. Flippers large, measuring about 4- of the total length of the body. Baleen with the bristles black. The number of the plates up to 400 (according to Dr. Guldberg) ; their greatest length (according to Dr. Nansen) 930 millim., not including the bristles. Jaws long, being to the total length as 1 to 4|. EXPLANATION OF THE PLATES. PLATE XXV. Fig. 1. Side view of Balcenoptera borealis, male. 2. Lower surface of ditto. PLATE XXVI. Fig. 1. Lower surface of Balcenoptera borealis, female. 2. One of the whitish spots on the skin; enlarged. PROC. ZOOL. Soc-1886, No. XVIII. 18 |
