CHAPTER XV

BERYCOIDEI

=THE Berycoid Fishes.=—We may place in a separate order a group of fishes, mostly spiny-rayed, which appeared earlier in geological time than any other of the spinous forms, and which in several ways represent the transition from the isospondylous fishes to those of the type of the mackerel and perch. In the berycoid fishes the ventral fins are always thoracic, the number of rays almost always greater than I, 5, and in all cases an orbitosphenoid bone is developed in connection with the septum between the orbits above. This bone is found in the _Isospondyli_ and other primitive fishes, but according to the investigations of Mr. E. C. Starks it is wanting in all percoid and scombroid forms, as well as in the _Haplomi_ and in all the higher fishes. This trait may therefore, among thoracic fishes, be held to define the section or suborder of _Berycoidei_.

These fishes, most primitive of the thoracic types, were more abundant in Cretaceous and Eocene times than now. The possession of an increased number of soft rays in the ventral fins is archaic, although in one family, the _Monocentridæ_, the number is reduced to three. Most of the living _Berycoidei_ retain through life the archaic duct to the air-bladder characteristic of most abdominal or soft-rayed fishes. In some however, the duct is lost. For the first time in the fish series the number of twenty-four vertebræ appears. In most spiny-rayed fishes of the tropics, of whatever family, this number is retained.

In every case spines are present in the dorsal fin, and in certain cases the development of the spinous dorsal surpasses that of the most extreme perch-like forms. In geological times the Berycoids preceded all other perch-like fishes. They are probably ancestral to all the latter. All the recent species, in spite of high specialization, retain some archaic characters.

=The Alfonsinos: Berycidæ.=—The typical family, _Berycidæ_, is composed of fishes of rather deep water, bright scarlet or black in color, with the body short and compressed, the scales varying in the different genera. The single dorsal fin has a few spines in front, and there are no barbels. The suborbitals are not greatly developed.

The species of _Beryx_, called in Spanish _Alfonsino_, _Beryx elegans_ and _Beryx decadactylus_, are widely distributed at moderate depths, the same species being recorded from Portugal, Madeira, Cuba, the Gulf Stream, and Japan. The colors are very handsome, being scarlet with streaks of white or golden. These fishes reach the length of a foot or more and are valued as food where sufficiently common.

Numerous species of _Beryx_ and closely allied genera are found in all rocks since Cretaceous times; _Beryx dalmaticus_, from the Cretaceous of Dalmatia, is perhaps the earliest. _Beryx insculptus_ is found in New Jersey, but no other Berycoids are yet known as fossils from North America. _Sphenocephalus_, with four anal spines, is found in the chalk, as are also species of _Acrogaster_ and _Pycnosterinx_, these being the earliest of fishes with distinctly spiny fins.

The _Trachichthyidæ_ are deep-sea fishes with short bodies, cavernous skulls, and rough scales. The dorsal is short, with a few spines in front. The suborbitals are very broad, often covering the cheeks, and the anal fin is shorter than the dorsal, a character which separates these fishes from the _Berycidæ_, in which group the anal fin is very long. The belly has often a serrated edge, and the coloration is red or black, the black species being softer in body and living in deeper water. Species of _Hoplostethus_, notably _Hoplostethus mediterraneus_, are found in most seas at a considerable depth. _Trachichthys_, a genus scarcely distinguishable from _Hoplostethus_, is found in various seas. The genus _Paratrachichthys_ is remarkable for the anterior position of the vent, much as in _Aphredoderus_. Species occur in Japan and Australia. _Gephyroberyx_, with the dorsal fin notched, is known from Japan (_G. japonicus_) and Madeira (_G. darwini_).

We may also refer to the _Trachichthyidæ_ certain species of still deeper waters, black in color and still softer in texture, with smaller scales which are often peculiar in form. These constitute the genera _Caulolepis_, _Anoplogaster_, _Melamphaës_, and _Plectromus_. In _Caulolepis_ the jaws are armed with very strong canines.

Allied to the _Trachichthyidæ_ are also the fossil genera _Hoplopteryx_ and _Homonotus_. _Hoplopteryx lewesiensis_, from the English chalk, is one of the earliest of the spiny-rayed fishes.

=The Soldier-fishes: Holocentridæ.=—The soldier-fishes (_Holocentridæ_), also known as squirrel-fishes, Welshmen, soldados, matajuelos, malau, alehi, etc., are shore fishes very characteristic of rocky banks in the tropical seas. In this family the flesh is firm and the large scales very hard and with very rough edges. There are eleven spines in the dorsal and four in the anal, the third being usually very long. The ventral fins have one spine and seven soft rays. The whole head and body are rough with prickles. The coloration is always brilliant, the ground hue being scarlet or crimson, often with lines or stripes of white, black, or golden. The fishes are valued as food, and they furnish a large part of the beauty of coloration so characteristic of the fishes of the coral reefs. The species are active, pugnacious, carnivorous, but not especially voracious, the mouth being usually small.

The genus _Holocentrus_ is characterized by the presence of a large spine on the angle of the preopercle. Its species are especially numerous, _Holocentrus ascenscionis_, abundant in Cuba, ranges northward in the Gulf Stream. _Holocentrus suborbitalis_, the mojarra cardenal, is a small, relatively dull species swarming about the rocks of western Mexico. _Holocentrus spinosissimus_ is a characteristic fish of Japan. Many other species abound throughout Polynesia and the East Indies, as well as in tropical America. _Holocentrus ruber_ and _Holocentrus diadema_ are common species of Polynesia and the East Indies. Other abundant species are _H. spinifer_, _H. microstomus_, and _H. violascens_.

_Holocentrus marianus_ is the marian of the French West Indies. _Holocentrus sammara_, and related large-mouthed species occur in Polynesia.

In _Myripristis_ the preopercular spine is wanting and the air-bladder is divided into two parts, the anterior extending to the ear. _Myripristis jacobus_ is the brilliantly colored candil, or "Frère Jacques," of the West Indies. Species of _Myripristis_ are known in Hawaii as _u-u_. A curious method of catching _Myripristis murdjan_ is pursued on the Island of Hawaii. A living fish is suspended by a cord in front of a reef inhabited by this species. It remains with scarlet fins spread and glistening red scales. Its presence is a challenge to other individuals, who rush out to attack it. These are then drawn out by a concealed scoop-net, and a fresh specimen is taken as a decoy. _Myripristis pralinius_, _M. multiradiatus_, and other species occur in Polynesia. _Ostichthys_ is allied to _Myripristis_ but with very large rough scales. _Ostichthys japonicus_ is a large and showy fish of the waters of Japan. _Ostichthys pillwaxi_ occurs at Honolulu. _Holotrachys lima_ is a small, brick-red fish with small very rough scales found throughout Polynesia.

Fossil species of _Holocentrus_, _Myripristis_, and related extinct genera occur in the Eocene and Miocene. _Holocentrus macrocephalus_, from Monte Bolca Eocene, is one of the best known. _Myricanthus leptacanthus_ from the same region, has very slender spines in the fins.

=The Polymixiidæ.=—The family of _Polymixiidæ_, or barbudos, is one of the most interesting in Ichthyology from its bewildering combination of characters belonging to different groups. With the general aspect of a Berycoid, the ventral rays I, 7, and the single dorsal fin with a few spines, _Polymixia_ has the scales rather smooth and at the chin are two long barbels which look remarkably like those of the family of _Mullidæ_ or _Surmullets_. As in the _Mullidæ_, there are but four branchiostegals. In other regards the two groups seem to have little in common. According to Starks, the specialized feelers at the chin are different in structure and must have been independently developed in the two groups. In _Polymixia_, each barbel is suspended from the hypohyal; three rudimentary branchiostegals forming its thickened base. In _Mullus_, each barbel is suspended from the trip of a slender projection of the ceratohyal, having no connection with the branchiostegals. _Polymixia_ possesses the orbitosphenoid bone and is a true berycoid, while the _Mullidæ_ are genuine percoid fishes.

Four species of _Polymixia_ are recorded from rather deep water: _Polymixia nobilis_ from Madeira, _Polymixia lowei_ from the West Indies, _Polymixia berndti_ from Hawaii, and _Polymixia japonica_ from Japan. All are plainly colored, without red.

=The Pine-cone Fishes: Monocentridæ.=—Among the most extraordinary of all fishes is the little family of _Monocentridæ_, or pine-cone fishes. _Monocentris japonicus_, the best-known species, is common on the coasts of Japan. It reaches the length of five inches. The body is covered with a coat of mail, made of rough plates which look as though carelessly put together. The dorsal spines are very strong, and each ventral fin is replaced by a very strong rough spine. The animal fully justifies the remark of its discoverer, Houttuyn (1782), that it is "the most remarkable fish which exists." It is dull golden brown in color, and in movement as sluggish as a trunkfish. A similar species, called knightfish, _Monocentris gloriæ-maris_, is found in Australia. No fossils allied to _Monocentris_ are known.