WORMS, MOSS-POLYPS, SPONGES, ETC. 115 
There are few objects more interesting to watch 
than a sponge in action, but with us, unfortunately, 
the only native sponges of consequence are either 
thinly-branched or encrusting forms, which scarcely 
permit of observations being-made upon their man- 
ner of living. One of these is the Microsciona 
prolifera, a rather scanty creeper on rocks and 
shells, having when fresh a bright red color. 
When full-grown it rises up into bunchy masses, 
measuring six inches or more across, which may 
be found scattered between the sedges of the sand 
where the latter has been left exposed at low-water. 
A much more delicate species, readily distinguished 
by its long and slender ‘ oculated’ branches, is the 
Chalina arbuscula, whose habitat appears to extend 
along the greater part of the Atlantic coast. 
The ‘ sea-bread’ or ‘ sea-crackers,’ rounded yel- 
lowish masses of an exceedingly light texture, which 
sometimes appear after a storm, are also skeletal 
parts of sponges, but their closely-packed and re- 
markably fine fibrous threads are composed princi- 
pally of silica instead of horn, and thus approxi- 
mate the type of the large and important group of 
silicious sponges, to which the ‘glass rope’ and 
‘Venus’s flower-basket,’ two of the most exquisite 
of nature’s objects, also belong. The sea-bread 
(Suberites) has been dredged alive on the Massa- 
chusetts coast, and it has therefore been conjec- 
tured that its home must extend to that region. 
Much more insignificant than the preceding is 
the form (Cliona) that attacks oyster- and elam- 
shells, burrowing into their midst from all direc- 
