Sea-Shells and their Occupants 147 



ail our precipitious coasts. Finally, I would say that a good 

 field glass is indispensable to the bird-watcher by the sea in 

 August. 



Charles Dixon. 



SEA-SHELLS AND THEIR OCCUPANTS. 



One of the greatest delights of many who make annual 

 visits to the sea is the collecting of specimens from the shore. 

 Shells are always especially sought after. Well-illustrated 

 works on British marine conchology are expensive. The 

 great work of Gwyn Jeffreys published more than thirty years 

 ago still keeps its place as the standard work ; equally 

 valuable is Forbes and Hanley's " History of the British 

 Mollusca " of fifty years' antiquity. It is from this latter 

 work that the appended plates have been selected. 



We do not for a moment deprecate mere collecting, but 

 would emphasise that the observation of the life-cycle of a 

 single species is of infinitely greater interest, and has far 

 greater intellectual value, than concerning one's self, during 

 the seaside holiday, with collecting as many different sorts 

 of shells as possible. 



Such questions as the probable origin of molluscan life, 

 the influences of environment upon the shape and colour of 

 shells, also mimicry and protective coloration, may be offered 

 to the young conchologist for investigation in the field, or, 

 more correctly, on the shore. The following remarks will 

 serve to indicate what we mean. 



In all probability the majority of land and fresh-water 

 mollusca are descended from marine forms which have slowly, 

 very slowly, and during long periods of time, undergone a 

 change in their environment, either by gradual migration or 

 by enclosure of arms of the sea. In this connection the 



