THE 
AMERICAN NATURALIST. 
VoL. xu1.— MAY, 1879. — No. 5. 
ON THE DESTRUCTIVE NATURE OF THE BORING 
SPONGE, WITH OBSERVATIONS ON ITS 
GEMMULES OR EGGS. 
BY JOHN A. RYDER. 
N 1871 a vessel laden with marble was sunk in Long Island 
sound, and according to Prof. Verrill, the boring sponge has 
penetrated the exposed parts of the blocks for a depth of two to 
three inches from the surface. The canals or tunnels in a speci- 
men of this marble which I have examined, vary from one-fourth 
to an hundredth of an inch and less in diameter ; the canals are 
coated within with a thin film of dried sarcode of a brown color, 
which was orange-colored in life. Though the sarcode is dried, 
the needle-shaped spicules are plainly visible under a one-fifth 
inch lens, and display the form usually seen in the same species 
found on the coasts of Europe. The spicules, according to 
my measurements are , of an inch long, agreeing exactly 
with the length given by Mr. H. J. Carter as observed in 
British specimens, and about robo of an inch in diameter, 
and are, as is well known, siliceous. The specimen which 
I have seen, shows, in what appears to have been the inner por- 
tion of the block, a series of large branching canals which 
connect freely with each other in the most irregular way im- 
aginable; moreover, the form of the canals in transverse sec- 
tion is exceedingly variable, being oval or irregular as often as it 
is circular. These last facts, together with that of the great 
Variability in the calibre of the canals, leaves no doubt in my 
mind that it is the animal of the sponge which does the boring, 
and not marine worms which have politely abandoned their bur- 
VOL, XIII.—No. V. 
