Ventrals jugular, pointed: body covered with soft scales: all the fins soft: jaws, and front of the vomer, armed with several rows of sharp card or rasp-like teeth: gill-opening large with seven rays.
Body oval, moderately elongated: head compressed: three dorsals: two anals: one barbule at the extremity of the lower jaw: ventrals with six rays.
Body elongated: three dorsals: two anals: no barbule on the chin: ventrals with six rays.
Body elongated: head compressed: two dorsals; the first small: one anal: chin without barbules.
Body slender, elongated, compressed behind: two dorsals; the first short; the second dorsal, as well as the anal, long: chin with one or more barbules: ventrals with six or seven rays.
* I have followed Cuvier in the arrangement of the genera belonging to this family. It may be questioned, however, whether those which he has adopted are all of them groups of equal value, and whether some might not with more propriety be lowered to a subordinate rank. Without an extensive acquaintance with foreign species, it would be presumptuous to decide this point.
Body elongated, compressed behind: first dorsal but little elevated, and scarcely perceptible; the rays detached and hair-like, all, except the first, very minute: second dorsal, and also the anal, long: ventrals with six or seven rays.
Body elongated, compressed behind: only one long dorsal extending nearly to the caudal: anal long: chin with a single barbule: ventrals thick and fleshy, consisting of five rays.
Ventrals consisting of only a single ray; often forked: head large: body elongated: chin with one barbule: two dorsals; the second, as well as the anal, long.
Head depressed and very broad: body very much compressed behind: two dorsals; the first very small, scarcely perceptible; the second, as well as the anal, long: ventrals with the two first rays elongated.
Body deep, very much compressed; with both the eyes on the same side of the head: sides of the mouth, and generally the pectorals, unequal: dorsal and anal extending the whole length of the back and abdomen respectively: ventrals appearing like a continuation of the anal: branchiostegous membrane with six rays.
A single row of obtuse cutting teeth in each jaw; and generally a pavement of teeth on the pha-ryngeans: dorsal commencing in a line with the upper eye, and leaving, as well as the anal, a space between it and the caudal: form rhomboidal: eyes on the right side.
Jaws and pharyngeans armed with strong sharp teeth: dorsal commencing in a line with the upper eye, and terminating before the caudal: form oblong: eyes sometimes on the right, sometimes on the left side.
Jaws and pharyngeans with fine card-like teeth: dorsal commencing immediately above the upper lip, and reaching, as well as the anal, to very near the caudal: form rhomboidal: eyes generally on the left side.
Mouth irregular, and as it were twisted on the side opposed to the eyes, and furnished on that side only with fine velvet-like teeth, the upper side being without teeth: form oblong-oval: snout rounded, advancing beyond the mouth: dorsal commencing at the mouth, and reaching, as well as the anal, quite to the caudal.
(1. Solea). Pectorals of moderate size, and not very unequal.
(2. Monochirus). Pectoral on the side of the eyes extremely small; that on the side opposite rudimentary, or altogether wanting.
Ventrals united, forming a concave disk beneath the body: skin without scales.
Pectorals large, descending to the inferior surface of the body, then doubling forwards upon themselves, and finally uniting under the throat by a transverse membrane: a second, circular, concave disk behind the disk formed by the united ventrals: head broad and depressed; snout projecting: gill-opening small; branchiostegous membrane with four or five rays: one dorsal.
Pectorals large, uniting under the throat, and enclosing the disk of the ventrals: no second disk: mouth broad; both jaws, as well as the pharyngeans, armed with small pointed teeth: gill-opening closed at bottom; branchiostegous membrane with six rays.
(1. Cyclopterus). A first dorsal more or less obvious, with simple rays; a second, with branched rays, opposite the anal: body thick.
(2. Liparis). Only one, moderately long, dorsal: anal long: body smooth; elongated, compressed behind.
An oval flattened disk on the upper part of the head, composed of several transverse cartilaginous plates directed obliquely backwards, and toothed on their posterior margin: body elongated, covered with small scales.
Body very much elongated: skin thick and soft; the scales deeply imbedded, and scarcely apparent.
Gills opening by a small aperture on each side beneath the pectoral: dorsal and anal fins prolonged round the end of the tail, forming by their union a pointed caudal.
(1. Anguilla). Dorsal commencing considerably behind the pectorals: upper jaw shorter than the lower.
(2. Conger). Dorsal commencing a little behind, sometimes immediately above, the pectorals: upper jaw longest.
Gills opening by a small aperture beneath the pectorals: dorsal and anal not reaching to the end of the tail, which terminates in a point, and is itself without a fin.
Gills opening by a small aperture on each side: pectorals wanting: dorsal and anal uniting at the tail; low, sometimes scarcely distinguishable.
Gill-opening small, before the pectoral: body very much compressed, ribband-shaped: head extremely small; snout short: pectorals scarcely perceptible: dorsal and anal obsolete, uniting at the extremity of the tail.
Gills opening by a moderately large aperture; furnished with a distinct opercle and branchioste-gous membrane: body very much compressed: dorsal and anal uniting to form a pointed caudal; the dorsal rays articulated, but not branched.
Gill-opening very large; all the pieces of the opercle considerably developed: snout sharp; upper jaw capable of great extension, but when at rest shorter than the lower: dorsal and anal separated from the caudal by a small space; the dorsal furnished with simple articulated rays: caudal forked.
Branchiae in small round tufts disposed in pairs along the branchial arches; opercle large, confined on all sides by a membrane, with only a small hole for the external aperture; branchiostegous rays rudimentary: jaws complete, and free.