CHAP. XX.] FISHES. 441 



Seven genera occur in Britisli seas, viz. : Hijjpoglossus, Hippo- 

 r/lossoidcs, Wiomhcs, Phrijnorliomhus, Arnoglossus, Plcicronedcs 

 (Turbot), and Solea (Sole). There are 13 genera in the Atlantic 

 and 2.":> in the Pacilic/^4 being common to both ; and 2 found 

 only in the jNIediterranean. A Pacific genus, Synaptura, has 

 one species in the Mediterranean. 



Order IV.—PHYSOSTOMI. 



Family 5'.».— SILURII)^. (114 Genera, 547 Species,) 



" Fresh-water or marine, scaleless fishes, often with 1)ony 

 shields, and the head always furnished with barbels." 



DiSTPJBUTiox. — Tlie fresh waters of all the temperate and 

 tro})ical regions, those which enter the salt water keeping near 

 the coast. 



This extensive family is divided l)y Lr. Giinther into eight 

 sub-families and seventeen groups, the distribution of which is 

 as follows : — 



Sub-family 1 (Siluwd.e Homalopter.^) is confined to the 

 Old World. It consists of three groups : Clarina (2 genera, 

 Clarias and Hetcrohranchus) ranges over the whole area of the 

 Ethiopian and Oriental regions, to which it appears to be strictly 

 confined ; Plotosina (3 genera, Plotoms, Copidoglanis, and Ca ido- 

 glanis) ranges from the eastern coasts of Africa to Japan, Poly- 

 nesia, and Australia, in seas and rivers ; Chacina (1 genus, Chaca) 

 ranges from India to Borneo. 



Sub-family 2 (SiLURiD^ Heteropter^) is also confined to the 

 Old World ; it consists of one group, — Silurina, containing 19 

 genera, viz. : — Snccohranclms (4 sp.), India to Cochin Cliina and 

 Ceylon ; Silvrns (5 sp.), Palasarctic region from Central Europe 

 to Japan, China, and Afghanistan, and a species in Cochin China; 

 Siluriclithys (3 sp.). Cashmere, Java, and Borneo ; Wallago (2 sp.), 

 Hindostan, Sumatra, and Borneo ; Bclodontichtliys (1 sp.), Su- 

 matra and Borneo ; Eutropiichthys (1 sp.), Bengal ; Crypioptcrus 



