ACTINIARIA. 
183 
into eiglit equal compartments or cells by as many thin septa, ori- 
ginating in a labial rim or lip between the bases of the tentacula, which 
descend through the cylinder attached on the one side to the inner 
tunic of the body, and on the other to the stomach, which is thus 
retained in its position. 
The protruding portion of the polype is very delicate, tho internal 
viscera being, as it were, enclosed in a bladder formed of two very thin 
membranes in intimate union, so transparent as to permit a view of 
their arrangement. At the base of the body, where thickest, it coalesces 
with the base of the adjacent polype ; thus constituting the common 
cortical portion into which each animalcule retreats at will, by a process 
in many respects resembling that by which a snail draws in its horns, 
hn the greater number oi AsteTOidss this common portion secretes 
carbonate of lime, which is deposited in the meshes of its tissues 
either in gramiles or in crystalline spiculse, which imparts a solid 
consistency to the whole. The inner tissue meanwhile continues 
faltered, being prolonged throughout the polypiferous mass, lining the 
cell, the abdominal cavity, and the longitudinal canals which permeate 
tho whole polvpier, as well as the tubular net-work with which the 
Spaces between the canals is occupied. It is among these inner tissues 
that the buds or gemma; are generated, by whose increase and evolution 
the polype mass is enlarged, the shape and size depending on the 
manner in which the buds are evolved ; for in some, as in Peunatu- 
determinate spots only have the appropriated organization, while 
lri others, as in Alcyonium, the generative faculty appears to be unde- 
hued and more diffused. 
The Actiniabia. 
r Here we leave the group of polypes which form united families, 
■{■he Sea Anemones, of which the Actinia are the type, consist of 
^ ° a nthaires , which produce no polypiers, that is to say, of polypes 
whose covering remains always soft, and in whose interior nothing solid 
liS produced. This order is usually divided into two families — the 
^-tiiniadse, having the tentacles in uninterrupted circles, with no 
c °i’allum, and the Minyadime, having globose bodies, and very short 
te utacula. 
The modern aquarium exposes the spectator to many wonderful 
