SPONGES: 58) 
declared that any system which has been hitherto adopted can only be 
considered as provisional. 
These minute though beautiful beings exist in numbers that are only 
rivalled by the sands of the sea for multitude ; 
and the vast hosts of these creatures can be barely 
estimated even when we know that many large { 1 
cities are built wholly of the dead skeletons of Kyi 
these microscopic beings, and that in a single 
ounce of sand from the Caribbean Sea nearly 
four millions of those shells have been discovered. 
The first sub-class of these beings is the 
Foraminifera, so called on account of the tiny 
openings, or foramina, with which the pretty 
shells are pierced. Sometimes, however, this  Polystomella Lessoniana. 
shell is wanting, and its place is supplied by a 
cover composed of matted sand-grains, 
PORIFERA, 
WE now arrive at a large class of beings, which are by common consent 
allowed to form the very lowest link in the animal chain. The name 
PorIFERA is given to them because the whole of their surface is pierced with 
holes of various dimensions, the greater number being extremely minute, 
o 
Grantia compressa, 
while others are of considerable dimensions. The . well-known Turkey 
SPONGE, so useiul for the toilet, will afford a good example of the porous 
structure. 
The true living being which constitutes the Sponge is of a soft and almost 
gelatinous texture, to the unaided eye ; and with the aid of the microscope is 
found to consist of an aggregation of separate bodies like those of the 
Ameebz, some of which are furnished with long cilia. By the constant 
action of the cilia a current of water is kept up, causing the liquid to enter 
by innumerable pores with which the surface is pierced, and to be expelled 
through the larger orifices. A Sponge in full action is a wonderful sight ; the 
