The northern species (_Hyperoodon rostratum_) has often been recorded upon our own coasts; the first record of the stranding of this Whale was in the year 1717. In that year an example was found at Maldon, in Essex. Like the Beluga, _Hyperoodon rostratum_ gets lighter in colour with advancing years. The young are black; the old animals pale brown with some white about them. The under surface, however, is always greyish white. The length of this Whale reaches to at any rate 30 feet. But John Hunter had a specimen which he believed to be 40 feet in length. The specimen, however, consisted only of a skull, so that error might have crept in. It has already been mentioned that the old males have enormous maxillary crests. According to M. Bouvier, who has lately made an exhaustive examination of the anatomy of this Whale,[254] the females occasionally exhibit the same crests, which are thus presumably of the nature of spurs sometimes seen in old females among the Gallinaceous birds. The number of grooves upon the throat is in dispute in this Whale as in _Ziphius_. One pair is the usual allowance; but Kuekenthal found four in some embryos studied by him. Attention has already been called to the voice of Ziphioid Whales. _Hyperoodon_ neither "lows" nor "bellows," but "sobs"! _Hyperoodon rostratum_ is a gregarious Whale, going about in herds, or "gams" as they should technically be termed, of four to ten or even fifteen. This Whale {372} can leap right out of the water, and while in the air can turn its head from side to side, a capability which has not been mentioned in any other Whale. It can also stay under water for an unusually long period. Captain Gray,[255] who has made an accurate study of this species, states that so long a period as two hours is the limit of endurance; this event occurred in the case of a harpooned Whale. FAM. 2. DELPHINIDAE.--This family, which includes the greater number of Cetacea, may thus be characterised:--Whales of small to moderate size. Teeth as a rule numerous, and present in the upper as well as in the lower jaw. Maxillae without large crests; the pterygoids, often meeting in the middle line, enclose an air space open behind. The anterior (five to eight) ribs are two headed, the posterior with tubercular head only. The sternal ribs are ossified.