Si 



would be necessary to compare together the fauna of every 

 country and region, which is not at present practicable for 

 want of the necessary data, as we possess lists of the molusca 

 of but few districts, and these more or less imperfect. As far 

 as is possible, with such information as can be procured, it has 

 been done by Dr. Philippi, in his valuable work upon the 

 molusca of the two Sicilies. 



" It only comes within the scope of my present communi- 

 cation to remark upon the distribution of the lower animals 

 within the limited area of our seas ; and from a desire not to 

 trespass upon the time and patience of the Society, by a dry 

 enumeration of all the species, with their various localities, I 

 will confine myself to the statement of such facts as I conceive 

 most important; even so, I feel called upon to intreat your 

 indulgence, as it will be necessary to mention not a few spe- 

 cies, the names of which will be particularly imintercsting to 

 those who have never bestowed attention upon this branch of 

 natural history. 



" The fauna of the British seas belongs to a division winch 

 has been denominated ' Celtic/ occupying the intermediate 

 space between the 'South European' and the 'Arctic' or 

 Northern. It contains some few species which belong to all 

 the three regions, being found both in Greeidand and the 

 Mediterranean; many Mediterranean species, which appear to 

 reach the northern limit of their range in our seas, and it also 

 furnishes the southern boundary to many arctic forms of 

 animal life. 



" Certain of the South European group of molusca oidy just 

 reach our coast, not occurring north of the British Channel 

 or the most southern shores of Ireland ; as examples of which, 

 I will mention lucina pecten, eapsa complanata, and castanea ; 

 cardium aculeatum and tuberculatum ; gastrochcena pholadia, 

 calvptroca sinensis, trochus exiguus, nassa varicosa, pleurotoma, 

 striolata, and the southern genus avicula. Two species which 

 appear to have their greatest development in the Mediter- 



