II. Gills three and a half; lower pharyngeals completely united into one bone, without median suture; palate toothless.
A single nostril on each side; teeth conical or incisor-like; a subocular shelf .......... 34. Pomacentridae.
Two nostrils on each side; anterior teeth usually strong and canine-like; teeth on pharyngeal bones conical or tubercular; no subocular shelf .......... 35. Labridae.
Two nostrils on each side; anterior teeth more or less coalesced into a beak; teeth on pharyngeal bones flat, tessellated; no subocular shelf .......... 36. Scaridae.
Fam. 1. Berycidae.—One or several of the suborbitals emitting an internal lamina supporting the eye; entopterygoid present. Anterior vertebrae without transverse processes; all or most of the ribs inserted on the transverse processes where these are developed. Two nostrils on each side. Gill-membranes free from isthmus; 4 to 10 branchiostegal rays; gills 4, a slit behind the fourth; pseudobranchiae. Lower pharyngeal bones separate. Ventral fins with 1 spine and 6 to 13 soft rays.
Fig. 400.—Beryx splendens, ⅓ nat. size. (After Goode and Bean.)
This family is remarkable for the retention of two archaic characters: the large number of rays to the ventral fins and the duct between the air-bladder and the digestive tract; the latter character is, however, not universal, and has only been found in two genera (Beryx and Holocentrum). The scaling of the body varies greatly, and so does the development of the spines in the vertical fins. Several genera (Melamphaes, Anoplogaster, Trachichthys, etc.) have the head studded with large muciferous cavities which are covered with a thin skin. The vent is usually situated far behind the ventral fin, but in Paratrachichthys, a genus closely allied to Trachichthys, it occupies a more anterior position, between the ventrals, whilst in Aphredoderus it shifts still further with age, opening on the throat in the adult.
The Berycidae were abundantly represented in Cretaceous deposits by Beryx and other genera more or less closely related to living forms, and they appear to have been the precursors of other Perciform Fishes. About 70 species, referred to 13 genera, are known to live at the present day, mostly at great depths, in the seas nearly all over the world. But one freshwater form is known, Aphredoderus sayanus, the little Pirate Perch of North America, growing to 5 inches in length. The largest marine forms (Beryx and Gephyroberyx) measure from 1 to 2 feet.
Recent genera: Beryx, Polymixia, Aphredoderus, Melamphaes, Plectromus, Scopelogadus, Anoplogaster, Caulolepis, Trachichthys, Paratrachichthys, Gephyroberyx, Myripristis, Holocentrum.