Ch. XXI.] NATURE OF PLOATING ANIMALS. 353 



some species, as Spirula, not unfrequently occm- also ; and 

 mollusks are common. These for the most part belong to 

 that division termed Pteropods, from the wing-like aspect 

 of their locomotive apparatus — and are either possessed of 

 a shell or not, but when so possessed it is usually of most 

 delicate structure and beautiful form. But there are other 

 oceanic shells (as Cariuaria and Janthina), of which men- 

 tion may be made ; and, moreover, some shell-less Nudi- 

 branchiata (as Glaucus and Scyileea) occur in the same 

 situation, as well as Tunicates, of which the lumiaous 

 Pyrosoma is a good example. Floating Crustacea are not 

 uncommon — either crabs of considerable size, as Neptunus 

 and Lupea, or the numberless forms of Stomapods, Amphi- 

 pods, Isopods, &c., which, with miuute Entomostraca, 

 constitute, perhaps, the bulk of the surface population of 

 the ocean. Certain worms, also, are occasionally met with, 

 and of Hydrozoa, the pelagic species are numerous and 

 interesting, and wUl receive their share of notice. On one 

 occasion, on the coast of China, a small Anemone attached 

 to a piece of straw which floated it, came in among the 

 produce of the net — a curious instance of the migratory 

 power of a fixed animal ; and it was no uncommon circum- 

 stance to find fixed Polyzoa and Foraminifera (Orbitolites) 

 attached to floating, leaves of Zostera or Sea-wrack. 



There being such a vast number of animals whose nor- 

 mal dwelling-place appears to be at, or near, the surface, it 

 would be readily imagiued that scarcely at any time — at all 

 events in calm weather — would the sea appear to be alto- 

 gether without inhabitants. And probably there is, strictly 

 speaking, no time when some living animals might not be 

 found, if proper means are used to detect them; but it is 

 no less true, that there are times when nothing is visible to 



