THE ZOOLOGIST 



No. 812.— February. 1909. 



ON THE VERTICAL AND B ATHYME TRIC AL DISTRI- 

 BUTION OF THE BRITISH NON-MARINE MOL- 

 LUSCA, WITH SPECIAL REFERENCE TO THE 

 COTTESWOLD FAUNA. 



By W. Harcourt-Bath. 



For some years past I have taken a particular and practical 

 interest in that branch of zoogeography and phytogeography 

 pertaining to vertical or perpendicular distribution. This line 

 of research and inquiry has been undertaken with special refer- 

 ence to the elucidation of the various problems connected with 

 the organic and physical environment of animals arid plants, 

 and the morphological characters assumed in consequence of the 

 preponderating influence of either one or the other of these two 

 opposing factors. 



As regards geographical or horizontal distribution, much has 

 been accomplished by various specialists in the different depart- 

 ments of biological science. On the other hand, the study of 

 vertical distribution has been negatively conspicuous by reason 

 of its almost total exclusion from the domain of geographical 

 investigation. This is at all events perfectly correct so far as the 

 fauna is concerned ; the flora, on the other hand, it is true, at 

 least in Europe, has received some share of attention at the hands 

 of Prof. Christ, Mr. Ball, and others, and in our own country more 

 especially by Dr. H. C. Watson. 

 Zool. 4th ser. vol. XIII., Februanj, J 909. e 



