Fam. 11. Dactylopteridae.—Head completely cuirassed; basis cranii simple; parietal bones meeting on the median line; two nostrils on each side. Gill-cleft broadly separated by scaly isthmus; gills 4; pseudobranchiae present. Vertebrae 20-22 (8-9 + 12-13), the first very elongate and formed by the fusion of three or four; ribs sessile, no transverse processes. Post-temporal fused with the skull; no supraclavicle; scapula and coracoid well developed, in contact with each other; pectoral rays divided into two parts, inserted on the scapula and on 4 elongate pterygials, of which 3 are in contact with the coracoid. Ventral fins close together, with 1 spine and 4 soft rays. Spinous dorsal shorter than the soft; anal without spines. Body covered with hard, rough scales.

The "Flying Gurnards," of which four species are known, belonging to a single genus (Dactylopterus), are inhabitants of the tropical and warm parts of the Atlantic and the Indian Ocean and Archipelago. They are remarkable, when adult, for the wing-like portion of the pectoral fins, by which they are able to move in the air like Exocoetus, but for shorter distances, and, unlike them, the wings are moved rapidly, the mode of flight resembling that of many forms of grasshoppers;[[740]] the young, however, have comparatively short pectorals, and were formerly regarded as belonging to a distinct genus (Cephalacanthus).

Division VIII.—JUGULARES.

No bony stay for the praeoperculum. Ventral fins jugular or mental. Gill-openings in front of the pectoral fin, the base of which is vertical or subvertical.

In a recently published note[[741]] I have alluded to the group of Physoclistous fishes for which I proposed to revive the old name Jugulares, pointing out that some of the forms previously grouped together as Trachinidae agree with the Gadidae, not only in the jugular position of the ventral fins, but also in the condition of the scapula and coracoid. Mr. Regan[[742]] has since been able to show that the Gadidae and Macruridae possess certain characters in common by which they may be separated not only from the other Jugulares, but even from the Acanthopterygians, and, as mentioned above (p. [646]), the Müllerian Sub-order Anacanthini may be maintained, after excluding the Pleuronectidae. That the Blenniidae are akin to Lycodes and its allies has long been admitted, and authors who have placed them in different divisions of their systems have had to confess the difficulty of referring certain genera to the one family rather than to the other. The fact that Lycodes and many forms previously associated with the Ophidiidae agree with the Macruridae and Gadidae in the diphycercal vertebral column and in the absence of spines to the fins is merely, it seems to me, the result of degradation; they probably form the terminal group of a series in which the vertebral column was originally homocercal and fin-spines were present, as is the case in most of the Blenniidae and Trachinidae and their near allies. All these families may be assumed to have evolved in several series, often on parallel lines, from some group closely related to the Berycidae; and the resemblance which their terminal forms bear to the Anacanthini is, as pointed out by Regan, probably to be ascribed to convergence, not to any close genetic affinity, as hitherto believed by many authors.

Fig. 427.—Pectoral arch and pelvis (left side) of A, Trachinus draco; B, Percophis brasilianus; cl, clavicle; cor, coracoid; pelv, pelvis; pt, pterygials; ptcl, post-clavicle; pte, post-temporal; sc, scapula; scl, supraclavicle.

The character of the position of the scapular foramen, either in the scapular bone or between it and the coracoid, which obtains in many genera of this division as well as in most of the Anacanthini, has proved to be unreliable even for the purpose of family definition; it is, however, of assistance in determining the relation of certain obscure, degraded forms placed by some authors with the Anacanthines, by others with the Blenniids.

Synopsis of the Families.

I. Pectoral rays attached to the scapula and to a series of pterygials of which only one or two are in contact with the scapula (see Fig. 427); ventral fins jugular, with 1 spine and 4 or 5 soft rays; anterior dorsal rays usually spinous or not articulated, often forming a detached fin.