NATURAL HISTORY. 



i>ome of the California!! rivers. These fishes are viviparous ; they have a large simple air-bladder. 

 and the stomach is destitute of pyloric appendages. 



FAMILY IV. GERRID^. 



The Gerridse comprise the one genus Gerres, represented by many species in tropical seas. 

 These fishes are oviparous ; they have rudimentary pyloric appendages. There is always an air- 

 bladder. 



FAMILY V. CHROMIDES. 



The fifth and last family is the Chromides, a large group of nineteen genera, distinguished by 

 their teeth, spines, and scales. They are fresh-water fishes, which are chiefly met with in the 

 tropics. One genus, Etroplus, occurs in Western India. The herbivorous species have the intestines 

 convoluted and the teeth lobed ; but there are carnivorous species, with simple pointed or conical 

 teeth. C/tromis galilceus is from the Sea of Galilee. Chromis, Sarotherodon, and Hemichromis are 

 African genera ; the others are all American. 



ORDER V. ACANTHOPTERYGII, OR SPINY-PINNED FISHES. 



The Acanthopterygii comprise a vast multitude of fishes, among which are some familiar 

 fresh-water forms which occur in the rivers of Great Britain. All these genera are characterised 



by having the inferior pharyngeal bones separated from each other, and by having some of the 

 of the dorsal, anal, and ventral fins developed into spines, and therefore wanting in the jointed cha- 

 racter which is seen in the remainder of the fin rays. The air-bladder is sometimes absent and 

 sometimes present, but it never possesses an air-duct to connect it with the throat. In the follow- 

 ing pages the genera are arranged according to the system developed by Dr. Giinther. In his 

 .arrangement of the fishes in the British Museum, five principal subdivisions of the order are 

 adopted ; the first of which includes sixteen out of the twenty groups of families, or smaller 

 natural divisions of the order. The first section of the order, comprising the sixteen divisions, is 

 distinguished by having a soft dorsal fin and an anal fin. The vent is always distant from the 

 extremity of the tail, and is placed behind the ventral fins whenever they exist. The first division 

 of this great group, termed Percifornies, comprises eleven families, in which the dorsal fin or fins 

 occupy the greater part of the back ; and the soft anal fin is similar to the soft dorsal. The ventral 

 fins ai i e placed under the throat; they have one spine and four or five well-developed rays. 



FAMILY I. PERCID.E. 



The type of the Perciform division is the Perch, best known from the Perca Jltti'iati/in, 

 which is widely distributed throughout the temperate parts of Europe and Russia in Asia, where 



it is confined to fresh waters. Two 

 other species are known, both of 

 which are found only in Canada 

 and North America. The Perch 

 is said to be wanting in the more 

 northern counties of Scotland, 

 though it inhabits Scandinavia 

 up to the 69 parallel of lati- 

 tude. These fishes feed on in- 

 sects, worms, and many small 

 fishes. The eggs are deposited 

 in long strings during spring, 

 and number more than a quarter 



of a million in a single fish. Yarrell observes that they live so well out of water that they 

 nre constantly to be seen alive in the markets of Southern Germany, from which they are taken 

 back again, if unsold, to the ponds from which they were brought. Occasionally this species 

 reaches a large size. One weighing nine pounds is said to have been caught in the Serpentine 

 in Hyde Park ; and Yarrell quotes Schiiffer as stating that the head of a Perch, which measures 

 nearly a foot in length, is preserved in the Church of Lulea, in Lapland. English specimens 



RIVER PERCH. 



