Form robust. Head very small and marked off from body by an ill-defined neck. No dorsal fin. Pectoral fins very broad and upturned. The color is pure white in the adult, except for a very narrow band of brownish on the edges of the flukes and flippers. The young are entirely brownish. Skull rather narrow and elongated. Eight to ten teeth in both jaws—cervical vertebræ all free. Vertebral formula: cervicals 7, dorsals 11, lumbars 9, caudals 23. Total, 50. Habitat: North Atlantic and North Pacific. BLACKFISH, PILOT WHALE, CA’ING OR GRINDHVAL _Globicephalus melas_ (Traill) Form robust. Head large and very round. Dorsal fin thick and triangular. Pectoral fins very long and narrow. The color is black throughout, except for a narrow fountain-shaped area of white on the throat, breast and belly. Greatest length, 30 feet. Skull broad and depressed. Premaxillæ strongly concave in front of nares. Vertebral formula: cervicals 7, dorsals 11, lumbars 12–14, caudals 28–29. Total, 58 or 59. Habitat: North Atlantic Ocean. BOTTLENOSE PORPOISE _Tursiops truncatus_ (Mont.) Head produced in the form of a beak. Strong teeth in both jaws. A well-developed dorsal fin. The color is dark gray on the head, back and sides, and the throat, breast and belly are white. Average length, 8 feet; greatest length, 12 feet. Rostrum tapering. Palate not grooved. Symphysis of mandible short. Forty to 50 teeth. Vertebral formula: cervicals 7, dorsals 13, lumbars 17, caudals 27. Total, 64. Habitat: North Atlantic Ocean. III. THE SKELETON OF THE CETACEA The skeletons of whales and porpoises are so frequently preserved in museums that, for the benefit of those who wish to understand more fully the Cetacea, a brief general description of the osteology is given below. Unfortunately, however, it is impossible to present the subject except in semi-technical language. The bones of the Cetacea are comparatively light and fragile, the hard, shell-like exterior being thin and the interior filled with spongy “cancellous tissue” which is considerably impregnated with oil. In structure they are exactly opposite to those of the Sirenia (the aquatic mammalian order including the sea cows, or manatees, and the dugongs), which have very heavy solid bones of almost flinty hardness. Cetacean bones are easily affected by weather, and if exposed to the sun, rain and wind for a comparatively short time the hard exterior becomes white and chalk-like. The whale’s skeleton is highly modified in adaptation to an aquatic existence and is very distinctive of the cetacean order. In a general view it is seen to be greatly elongated, the skull is pointed, the fore-limbs are short and flat and the hind-limbs are represented by nodules of bone; all these accompany a fish-like body which offers little resistance to its passage through the water.