Page:Encyclopædia Britannica, Ninth Edition, v. 12.djvu/706

688 688 ICHTHYOLOGY [CLASSIFICATION, half of the back. Branchiostegals numerous. Teeth tubercular or obtuse. Extinct. Genera : from Carboniferous and Permian formations Eurynotun, Benedenius, Mcsolepis, Eurysomus, Wardichthys, Chirodus (M Coy), Platysomus. SUBORDER VIII. Amioidei. Vertebral column more or less com pletely ossified, heterocercal. Body covered with cycloid scales. Branchiostegals present. Family 1. Cat ur idee. Notochord persistent, with partially ossified vertebrae ; homocercal ; fins with fulcra. Teeth in a single series, small, pointed. Extinct. Catarun, from the Oolite to the Chalk. Family 2. Lf.pt olcpidce. Scales cycloid. Vertebrae ossified; homocercal ; fins without fulcra ; dorsal short. Teeth minute, in bands, with canines in front. Extinct, but leading to the living representative of this suborder. Genera : Thrissops, Leptolepis, from the Lias and Oolite. These fishes, so far as the preserved parts are concerned, cannot be distinguished fromTeleosteous fishes, to which they are referred by some palaeon tologists. Family 3. Amiidce. Skeleton entirely ossified ; a single large gular plate ; hoinocei cal ; fins without fulcra ; a long soft dorsal fin. Abdominal and caudal parts of the vertebral column subequal in extent. Branchiostegals numerous. Amia. The &quot; Bow- Fin&quot; or &quot;Mud-Fish&quot; (A. calva) is not uncom mon in many of the fresh waters of the United States ; it grows to a length of 2 feet. Little is known about its habits ; small fishes, crustaceans, and aquatic insects have been found in its stomach. Wilder has observed its respiratory actions ; it rises to the surface, and, without emitting any air-bubble whatever, opens the jaws widely, and apparently gulps in a large quantity of air ; these acts of respiration are more frequently performed when the water is foul or has not been changed ; and there is no doubt that a conversion of oxygen into carbonic acid is effected, as in the lungs of aerial vertebrates. Fossil remains occur in Tertiary deposits of North America, which have been distinguished as Protamia and Hypamia, Subclass II. Teleostei. Heart with a non-contractile bulbus arteriosus ; intestine without spiral valve ; optic nerves decussating ; skeleton ossified, with completely formed vertebrae ; vertebral column diphycercal or homocercal ; branchiae frea The Teleostei form the majority of the fishes of the present fauna, and are the geological successors of the Palceichtkyes, undoubted Teleostei not ranging farther back than the Chalk period. This subclass comprises an infinite variety of forms ; and as, naturally, many Ganoid fishes lived under external conditions similar to those of certain Teleostei, and led a similar mode of life, we find not a few analogous forms in both series, some Ganoids resembling externally the Teleosteous Siluroids, others the Clupeoids, others the Chsetodonts, others the Scombresoces, &c. But there is no direct genetic relation between these fishes, as some naturalists have been inclined to believe. The Teleostei are divided into six orders : I. Acanthopterygii. Part of the rays of the dorsal, anal, and ventral fins non-articulated spines. The lower pharyn- geals separate. Air-bladder, if present, without pneumatic duct in the adult. II. Acanthopterygii Pharyngognathi. Part of the rays of the dorsal, anal, and ventral fins non-articulated spines. The lower pharyngeals coalesced Air-bladder without pneumatic duct. III. Anacanthini. Vertical and ventral fins without spinous rays. Ventral fins, if present, jugular or thoracic. Air-bladder, if present, without pneumatic duct. Lower pharyngeals separate. IV. Physostomi. All the fin-rays articulated j only the first of the dorsal and pectoral fins is sometimes ossified. Ventral fins, if present, abdominal, without spine. Air- bladder, if present, with a pneumatic duct. V. Lophobranchii. Gills not laminated, but composed of small rounded lobes, attached to the branchial arches. Gill- cover reduced to a large simple plate. A dermal skeleton replaces more or less soft integuments. VI. Plectognathi. A soft dorsal fin opposite to the anal ; sometimes elements of a spinous dorsal. Ventral fins none or reduced to spines. Gills pectinate ; air-bladder without pneumatic duct. Skin with rough scutes, or with spines, or naked. ORDER I. Acanthopterygii. Part of the rays of the dorsal, anal, and ventral fins are non- artieulated, more or less sharp-pointed spines. The lower pharyn geals are generally separate. Air-bladder, if present, without pneumatic duct in the adult. DIVISION 1. Acanthopterygii Perciformcs. Body more or less compressed, elevated or oMong, but not elongate ; the vent is remote from the extremity of the tail, behind the ventral fins if they are present. No prominent anal papilla. No superliranehial organ. Dorsal fin or fins occupying the greater portion of the back ; spinous dorsal well developed, generally with stiff spines, of moderate extent, rather longer than, or as long as, the soft ; the soft anal similar to the soft dorsal, of moderate extent or rather short. Ventrals thoracic, with one spine and with four or five rays. Family 1. Percidce. The scales extend but rarely over the vertical fins, and the lateral line is generally present, continuous from the head to the caudal fin. All the teeth simple and conical ; no barbels. No bony stay for the praeoperculum. A large family, represented by numerous genera and species in fresh waters, and on all the coasts of the temperate and tropical regions. Carnivorous. Fossil Percoids abound in some formations, for instance, at Monte Bolca, where species ot Labrax, Lates, Smerdis and Cydopoma (both extinct), Dules, Serranus, Apogon, Therapon, and Pristijioma have been recognized. Parapcrca is a genus recently discovered in the Marls of Aix-en-Provence. A species of Pcrca is known from the freshwater deposits of Oeningen. The living genera are Perca (Perch), Siniperca, Percichthys, Labrax (Bass), Lates, Psammopcrca, Percalabrax, Acerina (Pope), Lucioperca, Pilcoma, Bolcosoma, Aspro, Centropomus, Enoplosus, Centropristis, Anthias, Callanthias, Serranus (Sea-Perch), Anyper- odon, Prionodes, Plectropoma, Trachypoma, Polyprion, Grammistes, Rhypticus, Aulacocephalus, Myriodon, Diploprion, Mesoprion,, Glaucosoma, Dules, Therapon, Helotes, Pristipoma, Conodon, Hcemulon, Hapalogcnys, Diagramma, Hyper oglyphe, Lobotes, HistiO pterus, Gerres, Scolopsis, Hcterognathvdon, Dentex, Symphorvs, Synagris, Mcena, Smaris, Ccesio, Erythrichthys, Oligorus (Murray- Cod), Grystcs, Arripis, Huro, Ambassis, Apogon, Chilodiptcrus, Lanioperca, AcrOf&amp;gt;mna, Scombrops, Pmnatomus, Priacanthus, Cen- trarchus, Bryttus, Pomotis, Etelis, Niphon, Aprion, Apsilus, Penta- ceros, Velifcr, Datnioides, Percilia. Family 2. Squamipinnes. Body compressed and elevated, covered with scales, either finely ctenoid or smooth. Lateral line continuous, not continued over the caudal fin. Mouth in front of the snout, generally small, with lateral cleft. Teeth villiform orsetiform, in bands, without canines or incisors. Dorsal fin consisting of a spinous and soft portion of nearly equal develop ment ; anal with three or four spines, similarly developed as the soft dorsal, both being many-rayed. The vertical fins more or less densely covered with small scales. The lower rays of the pectoral fin branched, not enlarged ; ventrals thoracic, with one spine and five soft rays. Genera: Chcetodon, Chclmo, Heniochus, Holacanthus, Pomacan- thus, Scatophagus, Ephippus, Drcpane, Hypsinotus, Scorpis, Atypichthys, Toxotes. Some of these genera occur also in Tertiary formations. The majority of these fishes are inhabitants of the tropical seas, and abound chiefly in the neighbourhood of coral-reefs (Coral- Fishes). The beauty and singularity of distribution of the colours in some of the genera, as Chcetodon, Heniochus, Holacanthus,. is scarcely surpassed in any other group of fishes. They are of small size, and are carnivorous, feeding on small invertebrates. Family 3. Mullidoe. Body rather low and slightly compressed, covered with large thin scales, with or without an extremely fine serrature. Two long erectile barbels are suspended from the hyoid, and are received between the rami of the lower jaw and the opercula. Mouth in front of the snout, with the cleft lateral and r-ather short ; teeth very feeble. Eye lateral, of moderate size. Two short dorsal fins remote from each other, the first with feeble spines ; anal similar to the second dorsal. Ventrals with one spine and five rays. Pectorals short. Genera : Mullus and Upeneus (Red Mullets). Family 4. Sparidce (Sea-Breams). Body compressed, oblong, covered with scales, the serrature of which is very minute, and sometimes altogether absent. Mouth in front of the snout, with cleft lateral. Either cutting teeth in front of the jaws, or molar teeth on the side ; palate generally toothless. One dorsal fin, formed by a spinous and soft portion of nearly equal development. Anal fin with three spines. The lower rays of the pectoral fin are gene rally branched, but in one genus simple. Ventrals thoracic, with one spine and five rays. Genera : Canthnrus, Box. Scatharus Obtain, Crenidens, Tri-