The _Carangidæ_ or _Pampanos_ are tropical shore fishes, local or migratory to a slight degree. All these have from 24 to 26 vertebræ. In their pelagic relatives, the dolphins (_Coryphæna_), there are from 30 to 33; in the opah (_Lampris_), 45; in Brama, 42; while the great mackerel family (_Scombridæ_), all of whose members are more or less pelagic, have from 31 to 50. The mackerel (_Scomber scombrus_) has 31 vertebræ; the chub mackerel (_Scomber japonicus_), 31; the tunny (_Thunnus thynnus_), 39; the long-finned albacore (_Germo alalonga_), 40; the bonito (_Sarda sarda_), 50; the Spanish mackerel (_Scomberomorus maculatus_), 45. Other mackerel-like fishes are the cutlass-fishes (_Trichiuridæ_), which approach the eels in form and in the reduction of the fins. In these the vertebræ are correspondingly numerous, the numbers ranging from 100 to 160. _Aphanopus_ has 101 vertebræ; _Lepidopus_, 112; _Trichurus_, 159. In apparent contradiction to this rule, however, the pelagic family of swordfishes (_Xiphias_), remotely allied to the mackerels, and with even greater powers of swimming, has the vertebræ in normal number, the common swordfish having but 24. =The Eels.=--The eels constitute a peculiar group of soft-rayed ancestry, in which everything else has been subordinated to muscularity and flexibility of body. The fins, girdles, gill-arches, scales, and membrane bones are all imperfectly developed or wanting. The eel is perhaps as far from the primitive stock as the most highly "ichthyized" fishes, but its progress has been of another character. The eel would be regarded in the ordinary sense as a degenerate type, for its bony structure is greatly simplified as compared with its ancestral forms, but in its eel-like qualities it is, however, greatly specialized. All the eels have vertebræ in great numbers. As the great majority of the species are tropical, and as the vertebræ in very few of the deep-sea forms have been counted, no conclusions can be drawn as to the relation of their vertebræ to the temperature. It is evident that the two families most decidedly tropical in their distribution, the morays (_Murænidæ_) and the snake-eels (_Ophichthyidæ_), have diverged farthest from the primitive stock. They are most "degenerate," as shown by the reduction of their skeleton. At the same time they are also most decidedly "eel-like," and in some respects, as in coloration, dentition, muscular development, most highly specialized. It is evident that the presence of numerous vertebral joints is essential to the suppleness of body which is the eel's chief source of power. So far as known the numbers of vertebræ in eels range from 115 to 160, some of the deep-sea eels (_Nemichthys_, _Nettastoma_, _Gordiichthys_) having much higher numbers, in accord with their slender or whip-like forms.