332 CYPRINID.E. 



which reach far enough to cover the vent, and are deeply 

 concave internally : in the females the ventral fins are 

 smaller, shorter, and less powerful. 



In other fishes, besides occasional external sexual dis- 

 tinctions in particular species, it may be stated as a general 

 law, that in the males the head is sharper and longer ; the 

 latter effect being produced by a greater backward dilatation 

 of the operculum, and the body less deep in proportion to 

 its length than in the females, the abdominal line nearly 

 straight, in accordance with the general law, that in males 

 the respiratory cavity, and in females the abdominal cavity, 

 has the greater proportional size. In measuring the length 

 of the head with reference to the length of the body, the 

 sex causes little or no difference, the female obtaining in 

 depth what is wanting in length; her shorter body and head 

 afford the same comparative proportions. 



The Tench spawns about the middle of June, with some 

 variation depending on the season. Willughby says it hap- 

 pens when wheat is in blossom. Such coincident circum- 

 stances in the seasonal progress of animals and vegetables 

 particularly deserve to be studied, recorded, and remem- 

 bered : they may be made subservient to many useful pur- 

 poses ; one, which has a direct reference to fishing, will serve 

 as an illustration. Some London friends, who are enthusiastic 

 fly-fishers, know exactly when to leave home and find the 

 Mayfly on the water in different counties of England by the 

 flowering of certain shrubs and plants in the neighbourhood 

 of London. 



The female Tench, when ready to spawn, is usually at- 

 tended by two males, who follow her from one bunch of 

 weeds* to another, upon which the ova are deposited ; and 



* The broad-leaved pondweed, Potamogelon natans, is in some counties 

 called Tench-weed. 



