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A.— Collection of Fishes of the District, arranged 

 Zoologically. 



Class:— PISCES.— THE TRUE FISHES. 



The Fishes are back-boned animals, living in water, 

 with cold blood, and breathing by means of gills placed 

 at the sides of the throat ; the limbs are in the form of 

 fins, and the skin is generally covered with scales ; a row 

 of sense-organs along each side of the body forms a 

 conspicuous " lateral line." 



With the exception of the Mud-fishes (Dipnoi) which 

 are not marine, and do not occur in Europe, all the great 

 groups (Teleostei, Ganoidei, Elasmobranchii and Cyclo- 

 stomata) are represented in our district. Some members 

 of all the groups of fishes are edible, but by far the most 

 important groups from the economic point of view are 

 the Teleostei and the Elasmobranchii, and especially the 

 former. 



Sub-class I.— TELEOSTEI.— THE BONY 

 FISHES. 



With well developed jaws, fins, and scales ; with a 

 bony skeleton, having completely formed vertebrae, no 

 spiral valve in the intestine, tail evenly lobed externally, 

 gills free on gill arches underneath a gill cover ; air bladder 

 generally present. 



Order ACANTHOPTEKYGII. 



With stiff, unjointed spines in the fins ; the air 

 bladder has no duct. 



