$4 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [378] 
Lamellibranchs. 
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Pholas truncata.......-.-- 372 | Venus mercenaria......... 372 
Tagelus gibbus....--.----- 373 | Kellia planulata........-.. 374 
Mya arenaria ....--.---.-- 372 | Argina pexata .........-.- 372 
Mulinia lateralis...-...-.-.. 373 | Mytilus edulis.......... ane Ole 
Macoma fusca.......------ 372 | Modiola plicatula.......... 374 
Cumingia tellinoides. ...... 374 | M. hamatus......-........ 374 
Angulus tener............. 372 | Pecten irradians .......... 374 
Petricola pholadiformis.... 372 | Ostreea Virginiana .....-.- 374 
Ascidians. 
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Molgula Manhattensis. .-.. 375 Botryllus Gouldii.......--. 375 
RADIATA. 
Echinoderms. 
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Thyone Briareus......-.--- 376 | Asterias arenicola..-.. ... 376 
Acalephs. 
Page. Page. 
Hydractinia polyclina...... 376 | Halecium gracile.......-:. 376 
Il. 4.—ANIMALS INHABITING THE PILES AND TIMBERS OF WHARVES AND 
BRIDGES, BOTTOMS OF VESSELS, BUOYS, AND OTHER SUBMERGED 
WOOD-WORK. 
In these situations a large number of species may be found, but the 
majority of them are not peculiar to such stations. There are, however, 
quite a number of species that are nearly always found under these cir- 
cumstances, and others are directly dependent for their very existence 
upon submerged wood. Some of these, like the Teredo, for example, are 
of so great importance, owing to the injuries which they do to valuable 
property, that it seems desirable to make a special division for the 
animals ordinarily found in connection with wood-work of various kinds, 
whether injurious or not. 
On the piles of wharves and bridges various kinds of sea-weeds often 
grow in abundance, each species having a particular zone to which it is 
limited; but as these plants require light, they are found almost exclu- 
sively upon the outer rowsof piles and timber, and are most abundant on 
the outer side of the piles and on the southern exposures, where they get 
the most sunlight. These alge afford congenial homes to a considerable 
number of animals, most of which occur also among algie on the rocky 
Shores and in tide-pools. Beneath the wharves, where the piles are con- 
