The fishes with jugular ventrals we here divide into six groups, orders, and suborders: Jugulares, Haplodoci, Xenopterygii, Anacanthini, Opisthomi, and Pediculati. The last two groups, and perhaps the Anacanthini also, may well be considered as distinct orders, being more aberrant than the others.
For the most primitive and at the same time most obscurely defined of these groups we may retain the term applied by Linnæus to all of them, the name Jugulares. This group includes those jugular-fishes in which the position of the gills, the structure of the skull, and the form of the tail are essentially as in ordinary fishes. It is an extremely diversified and perhaps unnatural group, some of its members resembling Opisthognathidæ and Malacanthidæ, others suggesting the mailed-cheek fishes, and still others more degenerate. The fishes having the fins thus placed were long ago set apart by Linnæus, under the name of "Jugulares," Callionymus being the genus first placed by him in this group. Besides their anterior insertion, the ventrals in the Jugulares are more or less reduced in size, the rays being usually but not always less than I, 5 in number and more often reduced to one or two, or even wholly lost.
In general, the jugular fishes are degenerate as compared with the perch-like forms, but in certain regards they are often highly specialized. The groups showing this character are probably related one to another, but in some cases this fact is not clearly shown. In most of the jugular-fishes the shoulder-girdle shows some change or distortion. The usual foramen in the hypercoracoid is often wanting or relegated to the interspace between the coracoids, and the arrangement of the actinosts often deviates from that seen in the perciform fishes.
The Weevers: Trachinidæ.—Of the various families the group of weevers, Trachinidæ, most approaches the type of ordinary fishes. In the words of Dr. Gill, these fishes are known by "an elongated body attenuated backward from the head, compressed, oblong head, with the snout very short, a deeply cleft, oblique mouth, and a long spine projecting backward from each operculum and strengthened by extension on the surface of the operculum, as a keel. The dorsal fins are distinct, the first composed of strong, pungent spines radiating from a short base and about six or seven in number. The second dorsal and anal are very long. The pectorals have the lower rays unbranched, and the ventrals are in advance of the pectorals, and have each a spine and five rays. The species of this family are mostly found along the European and western African coast; but singularly enough a species closely related to the Old World form is found on the coast of Chile. None have been obtained from the intermediate regions or from the American coast. Two species are found in England, and are known under the name of the greater weever (Trachinus draco), about twelve inches long, and the lesser weever (Trachinus vipera), about six inches long. They are perhaps the most dreaded of the smaller English fishes. The formidable opercular spines are weapons of defense, and when seized by the fisherman the fish is apt to throw its head in the direction of the hand and lance a spine into it. The pungent dorsal spines are also defensive. Although without a poison gland, such as some fishes distantly related have at the base of the spines, they cause very severe wounds, and death may occur from tetanus. They are therefore divested of both opercular and dorsal spines before being exposed for sale. The various popular names which the weevers enjoy, in addition to their general designation, mostly refer to the armature of the spines, or are the result of the armature; such are adder-fish, stingfish, and sting-bull."
No species of Trachinidæ is known from North America or from Asia. In these fishes, as Dr. Boulenger has lately shown, the hypercoracoid is without foramen, the usual perforation lying between this bone and the hypercoracoid. A similar condition exists in the Anacanthini, or codfishes, but it seems to have been developed independently in the two groups. In the relatives of the Trachinidæ the position of this foramen changes gradually, moving by degrees from its usual place to the lower margin of the hypercoracoid. Species referred to Trachinus are recorded from the Miocene as well as Trachinus.
The extinct group of Callipterygidæ found in the Eocene of Monte Bolca seems allied to the Trachinidæ. It has the dorsal fin continuous, the spines small, the soft rays high; the scales are very small or wanting. Callipteryx speciosus and C. recticandus are the known species.
The Nototheniidæ.—In the family of Nototheniidæ the foramen is also wanting or confluent with the suture between the coracoids. To this family belong many species of the Antarctic region. These are elongate fishes with ctenoid scales and a general resemblance to small Hexagrammidæ. In most of the genera there is more than one lateral line. These species are the antipodes of the Cottidæ and Hexagrammidæ; although lacking the bony stay of the latter, they show several analogical resemblances and have very similar habits.
The Harpagiferidæ, naked, with the opercle armed with spines, and resemble sculpins even more closely than do the Nototheniidæ. Harpagifer is found in Antarctic seas, and the three species of Draconetta in the deeper waters of the North Atlantic and Pacific. These little fishes resemble Callionymus, but the opercle, instead of the preopercle, bears spines. The Bovichthyidæ of New Zealand are also sculpin-like and perhaps belong to the same family. Dr. Boulenger places all these Antarctic forms with the foramen outside the hypercoracoid in one family, Nototheniidæ. Several deep-sea fishes of this type have been lately described by Dr. Louis Dollo and others from the Patagonian region. One of these forms, Macrias amissus, lately named by Gill and Townsend, is five feet long, perhaps the largest deep-sea fish known. The family of Percophidæ, from Chile, is also closely allied to these forms, the single species differing in slight respects of osteology.
Fig. 443.—Pteropsaron evolans Jordan & Snyder. Sagami Bay, Japan.