Seven genera occur in British seas, viz.: Hippoglossus, Hippoglossoides, Rhombus, Phrynorhombus, Arnoglossus, Pleuronectes (Turbot), and Solea (Sole). There are 13 genera in the Atlantic and 23 in the Pacific, 4 being common to both; and 2 found only in the Mediterranean. A Pacific genus, Synaptura, has one species in the Mediterranean.
Order IV.—PHYSOSTOMI.
Family 59.—SILURIDÆ. (114 Genera, 547 Species.)
"Fresh-water or marine, scaleless fishes, often with bony shields, and the head always furnished with barbels."
Distribution.—The fresh waters of all the temperate and tropical regions, those which enter the salt water keeping near the coast.
This extensive family is divided by Dr. Günther into eight sub-families and seventeen groups, the distribution of which is as follows:—
Sub-family 1 (Siluridæ Homalopteræ) is confined to the Old World. It consists of three groups: Clarina (2 genera, Clarias and Heterobranchus) ranges over the whole area of the Ethiopian and Oriental regions, to which it appears to be strictly confined; Plotosina (3 genera, Plotosus, Copidoglanis, and Cnidoglanis) ranges from the eastern coasts of Africa to Japan, Polynesia, and Australia, in seas and rivers; Chacina (1 genus, Chaca) ranges from India to Borneo.
Sub-family 2 (Siluridæ Heteropteræ) is also confined to the Old World; it consists of one group,—Silurina, containing 19 genera, viz.:—Saccobranchus (4 sp.), India to Cochin China and Ceylon; Silurus (5 sp.), Palæarctic region from Central Europe to Japan, China, and Afghanistan, and a species in Cochin China; Silurichthys (3 sp.), Cashmere, Java, and Borneo; Wallago (2 sp.), Hindostan, Sumatra, and Borneo; Belodontichthys (1 sp.), Sumatra and Borneo; Eutropiichthys (1 sp.), Bengal; Cryptopterus (15 sp.), Java, Sumatra, and Borneo, with a species in the Ganges, in Siam, and (?) in Amboyna; Callichrous (10 sp.), Afghanistan to Borneo and Java; Schilbe (5 sp.), Tropical Africa; Eutropius (6 sp.), Tropical Africa and Central India; Hemisilurus (2 sp.), Java and Sumatra; Siluranodon (1 sp.), Nile; Ailia (2 sp.), Bengal; Schilbichthys (1 sp.), Bengal; Laïs (1 sp.), Java, Sumatra, Borneo; Pseudeutropius (6 sp.), India and Sumatra; Pangasius (7 sp.), Ganges, Sumatra, Java, Borneo; Helicophagus (2 sp.), Sumatra; Silondia (1 sp.), Ganges.
Sub-family 3 (Siluridæ Anomalopteræ) is confined to Equatorial America; it consists of the group Hypopthalmina, containing 2 genera: Helogenes (1 sp.), Hypopthalmus (4 sp.), from the country north of the Amazon, Surinam, and the Rio Negro.
Sub-family 4 (Siluridæ Proteropteræ) ranges over all the tropical and most of the temperate parts of the globe, except Europe and Australia. It consists of four groups: Bagrina (16 genera), ranging over most of the Old World and North America; Pimelodina (15 genera), confined to Tropical America, except one genus which is African; Ariina (10 genera), all Tropical regions; and Bagarina (3 genera), Oriental region. The distribution of the genera is as follows:—