[421] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 127 
species of Edwardsia, BE. lineata V., living in the interstices among 
ascidians and the tubes of Sabella and Potamilla. 
Sponges also occur in considerable numbers. Among them the most 
conspicuous is the Cliona sulphurea, a bright sulphur-yellow species, grow- 
ing into hemispherical or irregular, massive forms, of firm texture, the 
surface covered with scattered, low, wart-like, soft prominences, about 
an eighth of an inch in diameter, which contract when the sponge is 
dried, leaving shallow pits. The sponge commences as a boring species, 
on various dead shells, and as it grows it penetrates the shells in every 
direction, forming irregular holes and galleries, which continue to grow 
larger as more and more of the substance of the shell is absorbed, until 
the shells are reduced to a completely honey-combed, brittle mass, or a 
mere skeleton ; finally the sponge begins to protrude from the surface, 
and grows up into mammilliform masses, or small, rounded crusts, 
which continue to grow and spread in every direction, until finally they 
may form masses six or eight inches in diameter, with the base spread- 
ing over and enveloping various dead shells, pebbles, and the coral, 
Astrangia Dane, though it often happens that living specimens of the 
latter grow upon the sponge. Owing to the remarkable boring habits 
of this and other allied sponges, they are very important in the econ- 
omy of the sea, for they are the principal agents in the disintegration 
and decay of the shells that accumulate over the bottoms, thus per- 
forming the same function in the sea that fungi and insects perform on 
the land—the removal of dead organisms that otherwise would accu- 
mulate in vast quantities. In this work they are aided, in most regions, 
either by certain boring Annelids, (Dodecacerea, &c.,) or by various bor- 
ing mollusks, (Lithodomus, Pholas, Gastrochena, &c.,) but the greater 
part of this work seems to be effected by the sponges. 
Numerous species of Foraminifera were obtained on these and also on 
the rocky bottoms, but they have not yet been studied. The most com- 
mon kind occurs attached by one side to dead shells, alge, &e. It con- 
sists of several chambers arranged in a spiral manner, and to the naked 
eye resembles a minute depressed spiral shell. 
List of species inhabiting gravelly and shelly bottoms of the bays and 
sounds, 
ARTICULATA. 
Insects. 
Page. Page. 
Chironomus halophilus. .... 415| Muscide, larva ........... 339 
Pycnogonids. 
Page. Page. 
Phoxichilidium maxillare. ANS) PAUBMOR Seta t.2's a. = olen 409 
