PREFACE TO THE MOLLUSCA 



The general plan of classification adopted in this work is not 

 that of any single authority. It has been thought better to 

 adopt the views of recognised leading specialists in the various 

 groups, and thus place Ijefore the reader the combined results of 

 recent investigation. This method may, perhaps, occasion a 

 certain number of small discrepancies, but it is believed that the 

 ultimate effect will be to the advantage of the student. 



The classification adopted for the recent Cephalopoda is that 

 of Hoyle (' Challenger ' Kcports, Zooloiju, vol. xvi.), for the fossil 

 Cephalopoda (Nautiloidea) tliat of Fourd {Catalogue of the Fossil 

 Cephalopoda in the British Museum, 1888-91), and (Ammonoidea) 

 P. Fischer {Manuel de Conchyliologie, 1887). In the Gasteropoda 

 the outlines are those adopted by Pelseneer {Mem. Soe. Malacol. 

 Belg. xxvii. 1894), while the details are derived, in the main, 

 from r. Fischer. The Amphineura, h(iwever, have not been 

 reo-arded as a separate class. The grouping of the Xudi- 

 branchiata is that of Bergh (Semper, Reisen im Archiprl der 

 Philijipinen, ii. 3). The Pelecypoda are classified according to 

 Pelseneer's most recent grouping. 



Acknowledgment of the principal sources of information has 

 been made in font notes, iind a short list of leadhig authorities has 

 been appended to the chapters on anatomy, for the use of 

 students desirous to pursue the suliject further. In the case of 



IC\5<\01 



