T^he Shell and its Formation 33 



We are, therefore, in the position of liaving no well- 

 known name that will apply with anything approach- 

 ing accuracy or distinctness, in the way, for example, 

 that we denote beasts, birds, reptiles, and fishes ; and 

 there does not appear to be any prospect of getting 

 what we want. The naturalist is so used to the 

 term mollusk that he is not likely to seek or adopt 

 another, and tlie layman is too conservative to give 

 up so well-known and so inaccurate a name as Shell- 

 fish. The reader will understand why the word 

 " Shells " occupies a more important position in the 

 title of this volume than the makers and wearers of 

 those shells, and will not reo^ard it as beincr due to 

 sympathy with the early collectors and writers who 

 regarded the shell as of chief importance, and the 

 animal that secreted and lived in it as quite a 

 secondary matter. 



. In such a case accuracy is out of the question, for 

 many of the creatures described in these pages have 

 no apparent shell ; a greater number have absolutely 

 none when full-grown, though some of them begin 

 life with a rudimentary shell which does not develop. 

 But though the shell is not everything, it is so 

 characteristic of the Mollusca as a class, that we are 

 justified in giving some consideration to it at the start. 

 There is every reason for supposing that the 

 primitive molluscan shell was not much unlike that 

 which covers the Limpets to-day. Such a form gives 

 great strength with but a small expenditure of 

 material, and it is susceptible of modification in many 

 directions. A number of species whose anatomy 

 shows they are not intimately related, have retained 

 this form of shell to the present day. In proof of this 



