Sir W. Flower and many others are of opinion that there is but one species of Cachalot. But many names have been given to supposed other forms. The genus itself has even been divided, and to a set of vertebrae from the south Dr. Gray gave the perfectly superfluous name of _Meganeuron kreffti_. The "High-finned Cachalot" rests mainly upon the suggestions of Sir Robert Sibbald. It is supposed to have a high dorsal fin, and teeth in the upper as well as in the lower jaw. Common though it was asserted by its describer to be, there is not a bone, not a fragment even of a bone, alleged to belong to _Physeter tursio_ in any museum in the world! It seems premature, therefore, to include this mysterious creature in any list of Cetacea, though that was done by no less a naturalist than the late Mr. Thomas Bell. It is this creature round which most of the stories of ferocity congregate. It is held to be the monster from which Perseus delivered Andromeda, and which was about to devour Angelica upon the shore of Brittany. The fact of the matter is, that the Sperm Whale, like so very many other Whales, is world-wide in range; and those naturalists who did not believe in so wide a distribution found themselves obliged, in order to satisfy their own views, to create new species for those of distant localities. Hence the dozen or so of synonyms which refer to what is to be called _Physeter macrocephalus_. The genus _Kogia_ (sometimes written _Cogia_), the so-called "Pygmy Sperm Whale," is a southern form of much smaller dimensions than its gigantic ally just described. _Kogia_ does not exceed 15 feet or so in length. It differs from _Physeter_ also in the well-marked and falcate dorsal fin, in its generally delphinoid form, in the short snout, and the more normal (for a Whale) shape of the blow-hole, which is crescentic. There are also a number of osteological characters in which the two Physeterines differ from each other. In _Kogia_ all the cervical vertebrae are ankylosed together; the skull is short, though equally asymmetrical; the ribs are as many as twelve or {367} fourteen; the scapula has not the concave face that it has in _Physeter_. The functional teeth of the lower jaw seem to be reinforced by two on each side of the upper jaw. Moreover, the articulation of the ribs with the vertebrae does not show the very anomalous state of affairs that characterises _Physeter_, where the two heads of a rib may be upon one vertebra. While there is no doubt as to the generic distinctness of _Kogia_, there is again the same difficulty that is met with throughout the whole of the order in settling into how many species the genus requires dividing.