Tin; ANNALS 



AND 



MAGAZINE OF NATURAL HISTOIiV. 



[FOURTH SERIES.] 

 No. 113. MAY 1877. 



XXXV. — Malacohgical Notes. 

 By Robert Garner, F.L.S. &c. 



It seems to be a task neither easy nor free from doubt, to 

 assign a proper place in the Animal Kingdom to tlie Mollusca, 

 or, when their proper place is found, to fix their boundaries as 

 a subkingdom. It is evident that animals, both as they exist 

 now and as tliey have succeeded each otlier in past geological 

 time, are marked by different degrees of elaboration ; and tliis 

 leaves room for the doctrine of derivation from simpler pri- 

 mordial forms of the higher. This increasing differentiation 

 in the animal kingdom is also tacitly kept in view in taxonomy; 

 hence Mammalia are placed higliest in the whole animal series, 

 and ^lollusca in the non-vertebrate division of it. 



But the above greater or less elaboration, though a primary 

 consideration in general classification, is not by any means 

 the sole one. Were it so, and were we assured that one of 

 the higher forms is descended by an undeviating development 

 from one of the simpler, we ought to have, tracing the former 

 through the course of its formation, a sunmiary of all orga- 

 nology, which we have not. Strong are tlie influences which 

 the conditions of life (etliological as they arc termed) exert on 

 the course of development ; or, in other words, great are the 

 variations necessary to modify an organism for change of 

 habitat, food, or climate, or for its protection. Along with the 

 general plan and its greater or less elaboration ujion which 

 animals are formed, there are therefore revealed secondary 

 types of formation, wliich, whether realities or abstractions, 



Ann. tfc Mag. N. Hist. Ser. 4. Vol. xix. 25 



