September 1, 1898.] 



KNOWLEDGE. 



163 



By far the largest of all tbe toothed whales is the 

 gigantic sperm-whale, the typical representative of a family 

 characterized by the absence of teeth in the upper jaw of 

 the adult, while those of tbe lower jaw are very variable 

 both as regards form and number. In the sperm-whale, of 

 which the male attains a length of between fifty and sixty 

 feet, the lower teeth vary in number from fifty to sixty on 

 each side, and are characterized by their large size and 

 pointed crowns, upon which there is not a trace of enamel. 

 Another characteristic feature of this animal is the 

 enormous size of the head, which terminates in an abruptly 

 truncated muzzle of great depth, and in a cavity of which 

 is contained a peculiar oily substance, yielding when 

 refined the well-known spermaceti. An even more valuable 

 product of this animal is ambergris, which, while accumu- 

 lated as a concretion in the intestine, is generally found 



(Fig. 



FiQ. 3.— Tlio Iiiilian Porpoise. (From True, Bull. U.S. Xnt. Mi'ieum.) 



floating on the surface of the sea ; in appearance it is an 

 amber-coloured substance, containing a number of the 

 horny beaks of the squids on which the sperm-whale 

 subsists. 



Omitting mention of the lesser sperm-whale — the only 

 other member of the first division of the family — we pass 

 on to mention the bottle-nosed and beaked whales, 

 characterized by having all the lower teeth, with the 

 exception of a single pair, rudimentary, and concealed in 

 the gum. In the bottle-nases — so named from the extreme 

 convexity of the crown of the head of tbe adult males, 

 which rises suddenly above the short beak — there is but a 

 single pair of teeth, situated in the front of the lower jaw, 

 and even these are invisible during life. These whales, 

 of which there is but a single well-defined species 

 {Htjiieroijilon rostratus). although not exceeding some thirty 

 feet in length, are valuable on account of their oil, 

 as well as from yielding spermaceti from their skulls. In 

 contradistinction to the sperm-whale, they carry, in 

 common with the beaked whales, a large dorsal fin. 

 In the beaked whales, of which there are three existing 

 genera, the skull is produced into a long beak, of which 

 the upper half is formed by a solid bone of ivory-like 

 density ; while in the lower jaw there are either one or two 

 pairs of teeth, which, although variable in position, are 

 generally of large size. It is one of these 

 whales {Mesoplaidm liii/(irdi) which is alluded 

 to in tbe article on "Tusks and their Uses," 

 as being provided with teeth of such a size 

 as to actually imi^ede the free opening of 

 the mouth. From their general avoidance 

 of the neighbourhood of coasts, and their 

 apparently somewhat solitary habits, extremely 

 little is known of the life-history of the beaked 

 whales, of which the skeletons are but poorly 

 represented in our museums. At the present 

 day very rarely seen in the English seas, 

 during the pliocene period these whales must 

 been extremely numerous in the North Sea, since 

 their fossilized beaks are amongst the most common 

 vertebrate fossils obtained from the crags of Sufiblk and 

 Essex. The same deposits, together with others of corre- 

 sponding age on the Belgian coasts, have also yielded teeth 

 of a number of extinct whales, more or less closely allied 



to the sperm-whale, thus indicating that the latter is the 

 last survivor of a once numerous group. The teeth of 

 many of these fossil sperm-whales differed, however, from 

 those of their living cousins in having their crown capped 

 with enamel. 



In the general presence of numerous teeth in both the 

 upper and the lower jaws, the dolphins and their allies 

 the porpoises, killers, and white-whale differ fi'om all the 

 above-mentioned forms, and thus constitute a second family 

 — the iJclphinidiP. The group is a numerous one, which is 

 split up into a number of genera, some of which are by no 

 means easy to distinguish. They may, however, be roughly 

 ranged under two main divisions, in one of which the 

 muzzle is short and rounded, as in the porpoises and black- 

 fish, while in the other, as represented by the dolphins 

 1), it is produced into a longer or shorter beak, of 

 which the base is marked oft' fi'om the main 

 portion of the head by a distinct re-entering 

 angle. The most aberrant member of the 

 first group is the spotted Arctic narwhal, of 

 which a brief notice, accompanied by a figure, 

 was given in the article on " Tusks." Alhed 

 to the narwhal is the beautiful white-whale 

 iliehh/ii), which is likewise a northern species, 

 distinguished by its glistening white skin, the 

 absence of any tusk, and the presence of numerous well- 

 developed teeth in the fore part of the jaws ; neither of 

 these species having a back-fin. 



Although the name "porpoise "is applied indiscriminately 

 to several members of the family, it should properly be 

 restricted to a few comparatively small-sized species 

 characterized by the presence of some twenty-five small 

 and flattened teeth with spade-shaped crowns on either 

 side of each jaw. Porpoises are among the most common 

 and familiar of all cetaceans, their rolling gambols being 

 well known to all who have made a voyage ; but 

 whereas the common porpoise has a distinct back- 

 fin, in the species represented in our illustration that 

 appendage is lacking. Less familiar, on the other 

 hand, are the much larger and handsomely coloured 

 killers, or grampuses {(Jrca), differing by the great size 

 of their teeth (Fig. 2), which are usually twelve in number 

 on each side, and the great development of the back-fin. 

 Attaining a length of about twenty-five feet, the killer 

 derives its title from its rapacious habits ; a single specimen 

 having been known to swallow several whole seals in 

 succession, while not unfrequently several individuals have 

 been known to combine their forces to attack and kill the 

 larger members of the order. Killers may always be 

 easily recognized while swimming near the surface by the 



Fig. 4.— The Pitcillc Black-Fish. (From True, SnU. U. S. Nat. Mm.) 



have 



great height of their nearly vertical back-fins. Allied 

 cetaceans with smaller teeth (OireUa) frequent the Bay of 

 Bengal and ascend some distance up the Irrawadi. Another 

 well-marked typo is the black-fish, characterized by its 

 remarkably short and rounded head, the uniformly black 

 hue of the skin, and by the eight or twelve ". small . and 

 conical teeth being confined to the front portion of the jaws. 



