How far the species indicated range beyond the habitats whence they were received is yet to be discovered and recorded. No doubt their range is influenced by many local circumstances (peculiarities in the currents, and disposition of the food) that are not easily observed or understood. 2. MEGANEURON. Meganeuron, _Gray_, _l. c._ pp. 386, 387; _Synops. Whales & Dolph._ p. 4. The atlas vertebra subcircular, rather broader than high. The central canal subcircular, in the middle of the body, widened above. The rest of the animal not known; it is placed in _Catodontidæ_ because this family is the only one that has the atlas separate from the cervical vertebræ and of the simple form. 1. Meganeuron Krefftii. Meganeuron Krefftii, _Gray_, _P. Z. S._ 1865, p. 440; _Cat. Seals & Whales_, p. 388, figs. 94-97; _Synops. Whales & Dolph._ p. 4. Inhab. Australian seas. Atlas 13 inches wide. Family 7. PHYSETERIDÆ. Physeterina, _Gray_, _l. c._ pp. 386, 390. Physeteridæ, _Gray_, _Synops. Whales & Dolph._ p. 4. Head depressed, rounded in front. Blowers linear (often only the one on the left side open), at the back of the forehead. Mouth small, inferior, rounded. Dorsal fin compressed, falcate. Pectoral fin elongate, falcate. Skull short; crown concave; hinder part of the wall formed by the maxillaries, and divided, as it were, into two subequal parts by a central bony ridge, which is more or less twisted towards the right side. Upper jaw toothless. Atlas and cervical vertebræ all united into a solid mass. 1. PHYSETER. Physeter, _Gray_, _l. c._ pp. 196, 210, 386; _Synops. Whales & Dolph._ p. 4. Head large, rather depressed in front. Skull ⸺? Only known from Sibbald’s description, which, like his others, is very specific; and all his other accounts of animals have been proved to be correct. Mr. Flower has no faith in Sibbald’s account of this animal, and says, “If the Linnæan genus _Physeter_ is to be kept in abeyance until the rediscovery of Sibbald’s ‘_Balæna macrocephala tripinna_,’ it is to be feared that it may ultimately disappear altogether from zoological literature.”—_Trans. Zool. Soc._ vol. vi. p. 369. 1. Physeter tursio. Physeter tursio, _Linn._, _Gray_, _l. c._ p. 212; _Synops. Whales & Dolph._ p. 4. Inhab. North Sea, Scotland (_Sibbald_, 1687). Length 52 or 53 feet. 2. KOGIA. Kogia, _Gray_, _l. c._ pp. 196, 215, 386, 391; _Flower_, _Trans. Zool. Soc._ vol. vi. p. 114. Head moderate, blunt and high in front; left blower only open. Skull short and broad; the septum that divides the crown of the skull very sinuous, folded so as to form a funnel-shaped cavity. 1. Kogia breviceps. Kogia breviceps, _Gray_, _l. c._ pp. 217, 391; _Synops. Whales & Dolph._ p. 4. Inhab. Cape of Good Hope. Perhaps the next is the same species. 2. Kogia Macleayii. B.M.