90 



CELTIC PROVINCE. 



tinguishing epithet of Baltica or Balticus, but a little 

 consideration and comparison prove, beyond a ques- 

 tion, that these are the merest local varieties. High 

 up in the Baltic, there is a tendency towards a ming- 

 ling of such marine and fluviatile mollusks, as can 

 be inured to brackish water. Hence we find com- 

 mon forms of Limnceus, as L. palustris andpereger 

 (var. Balticus), Planorbis as P. alius, Bythinia and 

 Neritina, enumerated as inhabitants of the Baltic 

 sea. 



In the Channel Islands, and on the French coast 

 of this region, we have evidence of the influence of 

 a southern element, manifested by various well- 

 known forms of fishes and mollusks, which either 

 do not visit the shores of Britain, or are but rare 

 and occasional visitants. The tracing out the course 

 of this element, especially of so much of it as is 

 littoral, would be a task well worthy of the atten- 

 tion of an expert field-naturalist. We must look 

 to some of our able neighbours in France for the 

 undertaking of this investigation. Along her At- 

 lantic shores, some excellent naturalists have been 

 at work : indeed, the first impulse to the scientific 

 investigation of the distribution of marine animals 

 was given by French zoologists working amid the 

 sea-fauna of their own country. I allude especially 

 to the researches of Milne Edwards and his col- 

 league, Audouin. In their work, entitled " Recherches 

 pour servir a l'Histoire Naturelle du Littoral de la 

 France," published in 1832, they give an account 



