Page:Encyclopædia Britannica, Ninth Edition, v. 15.djvu/421

Rh C3TACEA.J nares, contracted at the middle of the rostrum, and expanding .again towards the apex. Vertebrae : C 7, D 11-12, L 10, C 23 ; total 51 or 52. Bodies of the first and second and sometimes the third cervical vertebrae united ; the rest free. Pectoral fin very large, ovate, nearly as broad as long. All the phalanges and mctacarpals broader than long. General form of body robust. Face short and founded. Dorsal fin near the middle of the back, very high and pointed. The animals composing this genus are met with in almost all seas from Greenland to Tasmania, but the number of species is still very uncertain. They are readily known, when swimming in the water, by the high, erect, falcate dorsal fin, whence their common German name of Schivert-fisch (Sword-fish). By English sailors they are generally known as &quot;Grampuses * or &quot;Killers.&quot; They are 399 in disposition, feeding principally on cephalopods. Their eminently sociable character constantly leads to their destruction, as when attacked they instinctively rush together and blindly follow the leaders of the herd. In this way many hundreds at a time are frequently. driven ashore and killed, when a herd enters one of the bays or fiords of the Faroe Islands or north of Scotland. Animals of this well-marked genus are found in nearly all seas, and their specific distinctions are not yet made out. Specimens from the Australian coasts, where they are generally called &quot; Blackfish,&quot; are quite indistinguishable, either by external or osteolo&quot;ical characters from those of the North Atlantic. Grampus. Teeth none in the upper jaw ; in the mandible few J. - * * J I* TT j J,U VUO 1UCU1UJ (3 to 7 on each side), and confined to the region of the symphysis C 7, D 12, L 19, C 30; total 68. General external char - Vertebrae : FIG. 50. Beluga or White Whalo (Delphinapferut Teucan ). From a specimen river St Lawrence, and exhibited in London, 1877. distinguished from all their allies by their great strength and ferocity, being the only Cetaceans which habitually prey on warm blooded animals, for, though fish form part of their food, they also attack and devour Seals, and various species of their own order, not only the smaller Porpoises and Dolphins, but even full-sized Whales, which last they combine in packs to hunt down and destroy, as Wolves do the larger Ruminants. Pseudorca. Teeth about -}. Cranial and dental characters generally like those of Orca, except that the roots of the teeth are cylindrical. Vertebra;: C 7, D 10, L 9, C 24; total 50. First to sixth or seventh cervical vertebrae united. Bodies of the lumbar ver tebrae distinguished from those of the preceding genera by being taken in the FIG. 51.- Grampus (Orca gladiator). From Hunter. more elongated, the length being to the width as 3 to 2. Pectoral fin of moderate size, narrow, and pointed. Dorsal fin situated near the middle of the back, of moderate size, falcate. Head in front of the blowhole high, and compressed anteriorly, the snout truncated. This genus was first known by the discovery of a skull in a sub- fossil state in a fen in Lincolnshire, named by Professor Owen Phoczena crassidcns. Animals of apparently the same species were afterwards met with in small herds on the Danish coast, and fully described by Reinhardt. Others subsequently received from Tasmania were supposed at first to indicate a different species, but comparison of a larger series of specimens from these extremely distant localities fails to establish any characteristic difference, and indicates an immense range of distribution for a species apparently so rare. Its length is about 14 feet, and its colour entirely black. Globiccphalus. Teeth |f^&amp;gt; confined to the anterior half of the rostrum and corresponding part of the mandible, small, conical, curved, sharp-pointed when unworn, sometimes deciduous in old age. Skull broad and depressed. Rostrum and cranial portion about equal in length. Upper surface of rostrum broad and flat. Premaxillne strongly concave in front of the nares, as wide at the middle of the rostrum as at the base or wider, and very nearly or completely concealing the maxillae in the anterior half of this region. Vertebra: C 7, D 11, L 12-14, C 28-29 ; total 58 or 59. Bodies of the anterior five or six cervical vertebrae united. Length of the bodies of the lumbar and anterior caudal vertebrae about equal to their width. Pectoral limb very long and narrow, the second digit the longest, and having as many as 12 or 13 phalanges, the third shorter (with 9 phalanges), the first, fourth, and fifth very short. Fore part of the head very round, in consequence of the great development of a cushion of fat, placed on the rostrum of the skull in front of the blowhole. Dorsal fin -low and triangular, the length of its base considerably exceeding its vertical height. The type of this well-marked genus is G. melas, the Pilot Whale, Ca ing Whale, or Grindhval of the Faroe islanders, which attains the length of 20 feet, and is of nearly uniform black colour, except the middle of the under surface, which is lighter. They are extremely gregarious, and, unlike the Killers, are mild and inoffensive acters much as in Globiccpkalus, but the fore part of the head less rounded, and the pectoral fin less elongated. But one species, G. griscus, is certainly known, about 13 feet long, and remarkable for its great variability of colour. It has been found, though rarely, in the North Atlantic and Mediterranean. A skull from the Cape of Good Hope, which differs slightly from that of the above, has been described under the name of G. ricliardsoni. Delphinus. Teeth very numerous in both jaws, more than fg, occupying nearly the whole length of the rostrum, small, close-set conical, pointed, slightly curved. Rostrum more or less elongated, and pointed in front, usually considerably longer than the cranial portion of the skull. Vertebrae : C 7,1) 12-14, L and C variable; total 51 to 90. Pectoral fin of moderate size, narrow, pointed, somewhat falcate. First digit rudimentary, the second longest, third nearly equal, fourth and fifth extremely short. Externally the head shows a distinct beak or pointed snout, marked off from the antenarial adipose elevation by a V-shaped groove. Dorsal fin rather large, triangular or falcate, rarely wanting. This is a large and heterogeneous genus, which probably ought to be divided, but, until more is known of the structure of many of the species than is at present attainable from the scanty materials in our collections, it is impossible to frame a system of subdivision upon a scientific basis. It seems preferable therefore, in stead of introducing new names into zoology for groups founded upon trifling differences in the length or width of the rostrum of the skull or the number of the teeth, which may or may not be correlated with other more important structural modifications, to keep provisionally at least the Linnaean term Dclphinus for what remains of the family, after eliminating the well-characterized genera previously described. The true Dolphins, Bottle-noses, or, as they are more commonly called by seafaring people, &quot; Porpoises,&quot; are found in considerable abundance in all seas, and some species are habitually inhabitants of large rivers, as the Amazon. They are all among the smaller members of the order, none exceeding 10 feet in length. Their food is chiefly fish, for the capture of which their long narrow beaks, armed with numerous sharp-pointed teeth, are well adapted, but some appear also to devour crustaceans and molluscs. They are mostly gregarious, and the agility and grace of their move ments in the water are constant themes of admiration to the spectators of the scene when a &quot;school of Porpoises&quot; is observed playing round the bows of a vessel at sea. The type of the genus FIG. 52. Common Dolphin (Delphinus delphis). From Reinhaidt. is the Common Dolphin of the Mediterranean (D. delphis, fig. 52), also found in the Atlantic, and of which a closely allied it&quot; not identical form is met with in the Australian seas (D.forstcri) and in the North Pacific (D. bairdii). The Tursio (D. tursio) is another British species of larger size and heavier build, with larger and less numerous teeth ; this and several allied forms probably constitute a natural subgroup. The White-beaked and White-sided Dolphins (D. albirostris and leucoplcurus) of the North Atlantic, and several others from the South and Pacific Seas, with comparatively broad and short rostrum to the skull and very numerous (80 to 90) vertebrae, constitute the genus Lagcnorhynchus of Gray. Others, with long narrow rostrum, are associated under the name of Steno, one of which from the Chinese seas (D. sinensis) has but 51 vertebras. This last is of a pure milk-white colour, but most of the species are variegated with glossy black, various shades of grey, and white, the latter chiefly on the under parts of the body. One species (D. pcronii) from the South Seas is remarkable for the absence of