The scales of the Cœlacanths were, in almost all the genera which compose the family, of great size; in some species, of the greatest size to which this kind of integument ever attained. Of a Cœlacanth of the Coal Measures, the _Holoptychius Hibberti_, the scales in the larger specimens were occasionally from five to six inches in diameter. Even in the _Holoptychius nobilissimus_, in an individual scarcely exceeding two and a half feet in length, they measured from an inch and a half to an inch and three quarters each way. In the splendid specimen of this last species, in the British Museum, there occur but fourteen scales between the ventrals, though these lie low on the creature’s body, and the head; and in a specimen of a smaller species,—the _Holoptychius Andersoni_,—but about seventeen. The exposed portion of the scale was in most species of the family curiously fretted by intermingled ridges and furrows, pits and tubercles, which were either boldly relieved, as in the _Holoptychius_, or existed, as in the _Glyptolepis_, as slim, delicately chiselled threads, lines, and dots. The head was covered by strong plates, which were roughened with tubercles either confluent or detached, or hollowed, as in the _Bothriolepis_, into shallow pits. The jaws were thickly set with an outer range of true fish teeth, and more thinly with an inner range of what seem _reptile_ teeth, that stood up, tall and bulky, behind the others, like officers on horseback seen over the heads of their foot-soldiers in front. The _double_ fins,—pectorals and ventrals,—were characterized each by a thick, angular, scale-covered centre, fringed by the rays; and they must have borne externally somewhat the form of the sweeping paddles of the Ichthyosaurian genus,—a peculiarity shared also by the double fins of the _Dipterus_. The _single_ fins, in all the members of the family of which specimens have been found sufficiently entire to indicate the fact, were four in number,—an anal, a caudal, and two dorsal fins; and, with the exception of the anterior dorsal, which was comparatively small, and bent downwards along the back, as if its rays had been distorted when young,[11] they were all of large size. They crowded thickly on the posterior portion of the body,—the anterior dorsal opposite the ventrals, and the posterior dorsal opposite the anal fin. The fin-rays of the various members of the family, and such of their spinous processes as have been detected, were hollow tubular bones; or rather, like the larger pieces in the framework of the Placoids, they were cartilaginous within, and covered externally by a thin osseous crust or shell, which alone survives; and to this peculiarity they owe their family name, Cœlacanth, or “hollow-spine.” The internal hollow, _i. e._ cartilaginous centre, was, however, equally a characteristic of the spinous processes of the _Coccosteus_. In their general proportions, the Cœlacanths, if we perhaps except one