7^\ 



BIOLOGY OF THE MOLLUSCA : 



Based chiefly upon a study of one of our commonest species, 



Helix aspersa. 



Address delivered ai ihc Aijiiual .Meeting, in ihe Town Hall, Hiinley, Oct. 14th, to 



Bv [OHN W. TA^■LOK. 



At the request of the Council of our Society 1 ha\e consented to fill 

 the ^■acan( }• at tliis Meeting caused by our valueci President being un- 

 expectedly pre\ ented from preparing the Annual Address which it has 

 been al\va)S customary for our Chairman to deliver, but the intimation 

 of the wish of the Council did not allow me much time for prepara- 

 tion, so I decided to offer some notes which I had already partially 

 prepared, bearing upon the. " Biology of the jNIollusca," and based 

 chiefly upon a study of one of our commonest species, Helix aspersa. 



Probably at no time in the history of the world have changes of 

 the organic inhabitants of the more primitive regions of the earth 

 pioceeded with such abnormal rapidity as at the present day; changes 

 which are almost entirely due to the enormous increase in the facilities 

 for rapid locomotion, which bring within comparatively easy reach 

 the most remote regions of the globe and subject the weak and simple 

 forms of animal and vegetable life in the more primitive countries to 

 the direct and immediate competition of the more advanced and 

 dominant species. 



Rapid changes are thus caused in the fauna and flora ot a relatively 

 weak region by the extirpation or expulsion of the native organisms, 

 which are supplanted by more highly organized and dominant species, 

 purposely or involuntarily introduced by the agency of man, and trans- 

 formations are thus effected which, in the ordinary course of diffusion, 

 would have taken thousands of years to accomplish, but which ma\- 

 now be consummated even during the short span of an individual life. 



Not only have animals and plants been rapidly and entirely exter- 

 minated, but man himself is almost equally subject to these natural 

 laws, and races of men have been or are in process of being destroyed 

 and have disappeared or will shortly disappear from the face of the 

 earth ; and this destructive process will, with the continued improve- 

 ments in quick and easy transport, become increasingly deadly, bring- 

 ing the stronger and weaker races more quickly into close contact and 

 competition, with fatal effects to the indigenous fauna and flora of 

 the weaker regions of the globe, and this natural process is more or 

 less in operation in every country. 



In this connection I may quote the remark of the late Capt. Hutton, 

 our great authority on New Zealand, who stated in conversation with 



