2S8 THE INHABITANTS OF THE SEA. 



imported into France, and the value of cameos produced in Paris 

 alone amounts to more than a hundred thousand pounds. A large 

 number are also cut in the small town of Oberstein on the Nahe 

 (a river flowing into the Rhine at Bingen), which has long been 

 famous for the manufactory of agate ornaments and trinkets, 

 and has now added this new branch of industry to the more 

 ancient sources of its prosperity. 



The Pteropods, or Wing-footers, move about by means of 

 two fin-like flaps, proceeding wing-like from the fore part of the 

 body. They have no disk to walk upon, nor arms for the 

 seizure of prey, like the cephalopods and gasteropods, but re- 

 semble them by the possession of a head distinct from the rest 

 of the body, which some, like the Hyaleas and Cleodorae, con- 

 ceal in a thin transparent or translucent shell, in which they 

 also hide their head and wings at the approach of danger, and 

 immediately sink to the bottom ; while others, like the blue and 

 violet Clios, beautifully variegated with light 

 red spots, are perfectly naked. They ge- 

 nerally inhabit the high seas, and are but 

 rarely drifted by storms or currents into the 

 neighbourhood of the land. They mostly 

 Hyaiea giobuioea. swim about freely, but sometimes also they 

 are found clinging by their wings to floating 

 sea-weeds. They are small creatures, but propagate so fast that 

 the Clio borealis and Limaema arctica form the chief food of 

 the colossal whale. 



While these two little pteropods, in spite of their minute pro- 

 portions, deserve to rank among the most important inhabitants 

 of the northern seas, the Mediterranean species belong mainly 

 to the genera Hyaiea, Cleodora, and Criseis — forms wholly 

 unknown to our own fauna except as waifs. Vast shoals of 

 these animals frequent the deeper parts of that sea, leaving 

 their remains strewed over its bed, between depths of from 

 one hundred to two hundred fathoms ; they are short-lived 

 creatures, and have tbeir seasons, being met with near the 



