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CELTIC PROVINCE. 



characteristics of the Celtic province are chiefly, 

 almost entirely, marked by the inhabitants of the 

 higher zones. This is strikingly exemplified by 

 the mollusca, especially by those genera of them 

 which are represented in the Littoral and Lami- 

 narian zones only; as Patella, Purpura, Littorina, 

 Otina, Lacuna, Scrobicularia, and Donax. Similar 

 instances might be adduced from among fishes, 

 articulate animals and radiata. The comparatively 

 few genera which have their species entirely con- 

 fined to deeper zones within this area, extend in 

 other regions to the shallower belts. 



The inhabitants of the median or coralline zone 

 around the British shores are numerous and vari- 

 ous, but scarcely so peculiar as those of the preced- 

 ing belts. Yet the general assemblage presents an 

 unmistakable aspect of its own. Shell-fish, espe- 

 cially carnivorous mollusks, the whelk tribe above 

 all, abound throughout it, varying numerically ac- 

 cording to the nature of the sea-bed and the 

 amount and kind of prey furnished by their hunt- 

 ing grounds. Bivalves of considerable beauty, espe- 

 cially clams and scallops, are found buried in num- 

 bers in its gravels and muddy sands, and Sertu- 

 larian zoophytes throng so as to form miniature 

 gardens, and around their graceful branches crawl 

 and hang diversified kinds of worms and nudi- 

 brancheous sea-snails, not unfrequently of consi- 

 derable beauty. The spider crabs are here plenti- 

 ful, with many peculiar crustaceans. And, as a 



