Ventral fins narrowly separated; pectoral fin divided into two portions; pterygials elongate .......... 11. Dactylopteridae.
Fam. 1. Scorpaenidae.—Head not or but incompletely cuirassed, usually with spines; basis cranii double; parietal bones often meeting on the median line, over the supraoccipital; two nostrils on each side. Gill-membranes free from isthmus; gills 3½ or 4; pseudobranchiae present. Vertebrae 24 to 37, the anterior praecaudals with sessile ribs bearing epipleurals, the posterior with transverse processes, often directed downwards, or forming haemal arches, bearing the rib and the epipleural. Post-temporal more or less distinctly forked, more or less firmly ankylosed to the skull; scapula and coracoid well developed, in contact with each other or separated by cartilage; pectoral rays inserted on the scapula and on 3 or 4 large, hour-glass or anvil-shaped pterygials, two of which are in contact with the coracoid. Ventral fins close together, with 1 spine and 3 to 5 soft rays. Spinous dorsal strong, usually longer than the soft, sometimes extending on the head; anal usually with 3 spines. Body covered with scales or naked.
A large family of carnivorous marine fishes, some descending to great depths, of nearly world-wide distribution, represented by three extinct genera (Ampheristus, Histiocephalus, Scorpaenoides) in the Eocene and by several species of Scorpaena in later formations. About 250 recent species are known. Principal genera: Sebastes, Setarches, Scorpaena, Pterois, Apistus, Minous, Pelor, Choridactylus, Centropogon, Gymnapistus, Amblyapistus, Pentaroge, Tetraroge, Gnathacanthus (Holoxenus), Agriopus, Synancia, Polycaulus.
Fig. 424.—Scorpaena grandicornis. (After Valenciennes.) × ½.
Great variety of form obtains in this family, from the Perch-like Sebastes to the extraordinary-shaped Tetraroge, Pelor, and Synancia. Many of its members are excellent examples of mimetic adaptation to the surrounding, resembling the rocks among which they live and being covered with dermal appendages simulating weeds. An interesting example of commensalism has been discovered by A. Alcock[[736]] in Minous inermis, off the coasts of India, which, wherever found, is always more or less incrusted with the Gymnoblastic Hydroid Stylactis minoi. Many of the Sebastes and their allies are of large size and used as food; some are viviparous, the young being produced in great numbers and very small in size. Scorpaena, Pterois, Pelor, and Synancia are dangerous for the stings from their dorsal spines, which are provided with poison glands.[[737]]
Fam. 2. Hexagrammidae.—Head not cuirassed, without strong spines; basis cranii double; a single nostril on each side. Gill-membranes free from isthmus; gills 4; pseudobranchiae present. Vertebrae 42 to 57, most of the praecaudals with transverse processes bearing the ribs and the epipleurals. Post-temporal forked; scapula and coracoid well developed, in contact with each other; pectoral rays inserted on the scapula and 4 anvil-shaped pterygials, 2 of which are in contact with the coracoid. Ventral fins close together, more or less behind the pectorals, with 1 spine and 5 soft rays. Spinous dorsal of usually rather feeble rays, nearly as long as or longer than the soft; anal elongate, with or without spines. Body covered with small scales.
Carnivorous fishes, mostly of large size, from the rocky coasts of the North Pacific. Some are highly valued as food. Twelve species, referable to 6 genera: Hexagrammus, Pleurogrammus, Agrammus, Ophiodon, Zaniolepis, Oxylebius. Hexagrammus and Pleurogrammus are remarkable in having 4 or 5 lateral lines on each side.
Fam. 3. Comephoridae.—Head not cuirassed, without spines; basis cranii simple; two nostrils on each side. Gill-membranes free or narrowly attached to isthmus; gills 4; pseudobranchiae present or absent. Vertebrae 42 to 64, some or most of the praecaudals with transverse processes bearing the ribs and the epipleurals. Post-temporal forked; scapula and coracoid well developed, in contact with each other or separated by cartilage; pectoral rays inserted on the scapula and on 4 anvil-shaped or plate-like pterygials, 2 of which are in contact with the coracoid. Ventral fins, if present, close together, with 1 spine and 3 to 5 soft rays. Spinous dorsal of rather feeble rays, as long as or shorter than the soft; anal spines feeble or absent. Body covered with small scales or naked.
Four genera, each with a single species: Anoplopoma (Scombrocottus), from the North Pacific from Unalaska to California; Triglopsis, from deep water in Lakes Michigan and Ontario; Cottocomephorus, from Lake Baikal, and Comephorus from the greatest depths of that lake. As in many bathybial forms, Comephorus is colourless and provided with very large eyes; ventral fins are absent and the skeleton is very thin and papery. As a result of this condition, the second suborbital is not produced over the cheek, a unique exception to the main characteristic of this division; but no doubt can be entertained as to the propriety of referring it to the neighbourhood of Anoplopoma, since the recently discovered Cottocomephorus may be regarded as a connecting link between the two genera. Comephorus is viviparous, and dies after parturition.[[738]] Jordan regards Triglopsis as a relic of a former Arctic marine fauna.