3992 Mollusks. 



Acephala Tunicata, 75 species. 



Acephala Lamellibranchiata, 181 „ 



Acephala Pallibranchiata or Brachiopoda, 5 „ 



Pteropoda, 4 „ 



Gasteropoda Prosobranchiata, 221 „ 



Gasteropoda Opisthobranchiata, 113 „ 



Pulmonifera, 101 „ 



Cephalopoda, 14 „ 



Questions now naturally arise, as to the best way of obtaining a 

 complete collection, and as to the advisability of seeking a British 

 series of specimens, to the exclusion of extending our researches to 

 the whole European Fauna. 



A British collection must be more expensive than one formed from 

 a wider range, inasmuch as many of the Mollusca, both Boreal and 

 Lusitanian, attain their extreme limits in our seas, and are conse- 

 quently much more rare. For example : Tellina balaustina may be 

 procured from the Mediterranean at a much cheaper rate than a well- 

 authenticated British specimen ; and for the purposes of science and 

 classification would be equally instructive. Again, a British collec- 

 tion, supposing it to be complete as such, would present many gaps 

 in the classification, and, without the aid of foreign species, would be 

 far from satisfactory to a scientific mind. Many also of our British 

 genera are represented by only one species ; and there is nothing 

 more interesting than an extensive series of shells, all constant to the 

 general features, and presenting so great a variety of specific differ- 

 ences : to me this is one of the most delightful portions of Natural 

 History, to perceive order and regularity springing out of apparent 

 chaos and confusion of forms. 



I refer again to the work of Messrs. Forbes and Hanley, who, un- 

 der the Conidse, allude to an instance illustrative of my meaning. 



" To a person unacquainted with exotic, and at the same time un- 

 versed in fossil Conchology, the association of the fusiform shells often 

 called Pleurotoma with Conus will appear unnatural. There is really 

 a very complete passage between them and the true cones ; although 

 the extremes of each have little besides the pOwSsession of a spire and 

 the canaliculated aperture in common." 



I will now conclude with a few words as to the remedy for the above 

 disadvantages. I propose that collectors should endeavour to form a 

 European instead of a mere British collection. This would greatly 

 extend the number of species, and would lead to a much more correct 



