1895.] Sponges: Recent and Fossil. 537 
The modern sponge is most familiar as an article of toilet 
use, varying in size from one as small as an egg to one that 
would fill a half-bushel basket; and differing in texture as 
much as in size. The gathering of this sort of sponge is a dis- 
tinct trade, pursued by fishermen in many quarters of the 
globe, but especially in the Mediterranean. The value of the 
fisheries for a single year (1871), as represented at a single 
port (Trieste), was over half a million dollars ($540,000). 
The examination of one of these sponges of commerce shows 
a porous structure, with a vast number of holes, some large, 
some small. The large ones are called “ oscula.” This porous 
body is but the skeleton, the animal matter, a sticky, gelatin- 
ous mass, having been destroyed in preparing the sponge for 
commercial purposes. If one of these aggregations of animal- 
cules be studied in a living state, an interesting sight is visible. 
A stream of water enters the smaller pores, is carrried by 
the branching canals through 
the interior, and is ejected 
from the larger openings or 
oscula. (Fig. 1.) The in- 
going streams carry with 
them the food of the colony ; 
the outgoing ones take away, 
the waste or insoluble parti- 
Fic 1. Portion of sponge, highly mag- cles, and the water cleared of 
sara an ia miatea Aai the food suitable for the 
ofthe water. (After T. Rymer Jones.) growth of the individuals 
among which it has passed. The water is drawn into the 
sponge mass by the action of rapidly vibrating cilia or hairs, 
and it is forced out by the constant inflow thus created. 
A close examination of the skeleton shows it to be made up 
of multitudes of fibres, sometimes calcareous, sometimes sili- 
ceous. In most instances siliceous spicules are found in great 
abundance, though these are, in certain forms, calcareous. The 
spicules are most diversified in form. Some are long, straight 
and bar-like, pointed at one or both ends or else club-shaped ; 
some are provided with three, four, six or many branches; 
sometimes spines are produced, at the tips or on the sides; 
