6 MARINE AND FRESHWATER FISHES 



together in shoals according to their sizes, the smaller and 

 larger individuals keeping to themselves, and repelling the 

 intrusion of those that materially differ from them in this 

 respect ; a similar phenomenon has been observed in the 

 case of many gregarious marine species. Perch may attain 

 to a weight of as much as five or six pounds, one scaling 

 two pounds, however, being considered a fine fish. The 

 spawn of the Perch is a very beautiful object, and is not 

 unfrequently deposited by the fish in the tanks of aquaria. 

 The individual eggs are very minute, about the size of 

 millet seeds, but when extruded are invested with and 



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Fig. 2. — the perch {Perta fluviatilis). 



bound together by a copious matrix of semi-transparent 

 mucilage, and in this form deposited in reticulated lace-like 

 bands upon or among water-weeds or other suitable sub- 

 merged objects. The spawning season of the Perch ranges 

 from March to June. The number of eggs contained 

 in the roe of two fish, weighing respectively three pounds 

 two ounces and two pounds eleven ounces, was calcu- 

 lated by Mr. Frank Buckland to amount to no less 

 than 155,620 in the former and 127,240 in the latter 

 of the two examples. Casts of these two fish are now 

 on view in the Buckland Museum. Perch obtained from 

 different localities are subject to considerable colour 



