MOLLUSCS, OB SHELL-FISH. 243 



The next form is a very interesting one it is the common 

 whelk, or "buckie" of Scotch children. Between tide- 

 marks it is usually small, but in deeper water grows to a 

 length of six inches, and in many places is much valued 

 both as food and bait. It is very widely distributed and 

 common, and, like so many other common shore Gastero- 

 pods, is very variable, tending especially to run into local 

 varieties. It is extraordinarily abundant between tide-marks 

 in the Firth of Forth, where it lives chiefly in mud and 

 sand, and is often beautifully coloured. The egg capsules 

 are very common objects in autumn and spring, both on the 

 shore rocks and cast up among the refuse on the sand. 

 They are interesting objects and well worth study. 

 Each capsule has a tough wrinkled coat and is of irregular 

 shape, and the capsules are aggregated together in masses 

 varying in size from a small cluster like half a lemon to a 

 mass as large as a child's head. The spawning season is in 

 autumn, though, as in many Molluscs, it seems to be of long 

 duration. Each capsule when laid contains 500-600 eggs 

 inclosed within a space of a quarter of an inch to half an 

 inch in diameter, so that some estimate may be formed of 

 the enormous number of eggs produced by the parent. 

 Relatively very few of these eggs, however, develop. For 

 some reason not yet adequately explained, some five or six 

 in each capsule get the start, and begin to develop rapidly. 

 As they do so they devour their less successful brethren, 

 and on opening the capsules one finds the infant monsters 

 with their transparent bodies distended by some seventy to 

 eighty undeveloped eggs. By the help of this food they are 

 enabled to remain within the egg-case until the shell is fully 

 formed, when, in spring, they finally leave it, and begin life 

 on their own account. This sacrifice of many eggs to the 

 few which develop is common among shore Gasteropods, but 

 it can be observed perhaps most readily in the common 

 whelk. 



Whelks are probably more or less familiar to most people, 

 so it is not necessary to describe them in very great detail 

 (see Fig. 70). The living animal is both interesting and 

 beautiful, and an attempt should be made to keep a few 

 specimens in confinement. To do this with success it is 

 necessary that they should be supplied with a considerable 



