168 PISCES. 



Tribe 1. Sclerodermi. Jaws with separated teeth. 



Fam. Ostracionidae (Trunk-fishes). Body coffer-like, triangular or quad- 

 rangular, often prolonged into horn-like processes ; with firm dermal armour 

 consisting of polyhedral bony plates, on which only the fins and tail are 

 movable. Ostracion triqueter L. (fig. 610), West Indies ; 0. quadricornis L., 

 West Africa. 



Fam. Balistidae (File-fishes). The body is laterally compressed, and the skin 

 is covered with rough granules, or with hard rhomboid scales, and is often 

 beautifully coloured. Balistes maculatus L., Atlantic and Indian Oceans. 



Tribe 2. Gymnodontes. The jaws modified into a beak, with 

 cutting undivided or double dental plate. Dorsal spines absent. 



Fam. Molidae. Orthagoriscus mola Bl. Sunfisb. 



Fam. Tetrodontidae [Globefishes, Sea-Hedgehogs.] Diodon hystrix L., 

 Atlantic and Indian Oceans ; Tetrodon cutaneus Gthr., St. Helena. 



Sub-order 3. Physostomi. With soft fins (malacoptervgians), with 



Fia. 610. Ottracion triqueter (regne animal). 



comb-shaped gills and separated jaw bones. Pelvic fins abdominal 

 or absent. Swimming bladder always with a ductus pneumaticus. 



Fam. Muraenidae (Eels). Murcsna helena L. ; Anguilla anguilla L. (vul- 

 garis~), Europe. At the breeding season in autumn they migrate from the 

 rivers into the sea, and there first attain sexual maturity. The reproductive 

 processes are not perfectly known, though male and female have been dis- 

 tinguished from one another, and the presence of both kinds of sexual organs 

 has been shown. In the spring the young eels migrate from the sea into the 

 rivers. Conger vulgaris Guv. , coasts of Europe. 



Fam. Gynmotidae. Gymnotus electricus L. (Electric eel). Lives in the swamps 

 and rivers of South America, attains a length of six feet, and can, by means of 

 its electric discharge, knock down even large animals, e.g., horses. Celebrated 

 by the experiments of A. v. Humboldt. 



Fam. Clupeidae (Herrings). With tolerably compressed body, which with 

 the exception of the head is covered by large, thin, easily-detached scales. 

 Clupea harengus L., the Herring of the northern seas. It appears every year 

 at certain times, in enormous shoals, on the Scottish and Norwegian coasts. 

 The principal takes occur in September and October. C. (Harengula) sprattus 

 L., the Sprat, North Sea and Baltic ; Engraulix encrasicliolm Bond., Anchovy ; 



