COMPARATIVE ZOOLOGY. 
250 
radiating canals, which ramify and open into a circular 
vessel, and a u veil,” or shelf, always running around the 
mouth of the disk. 129 
Class II.— Anthozoa. 
These marine animals, which by their gay tentacles con¬ 
vert the bed of the ocean into a flower-garden, or by their 
secretions build up coral-islands, 
have a body like a cylindrical 
gelatinous bag. One end, the 
base, is usually attached ; the 
other has the mouth in the cen¬ 
tre, surrounded by numerous 
hollow tentacles, which are cov¬ 
ered w T ith nettling lasso-cells. 
This upper edge is turned in so 
™ . * , o .. ,. as to form a sac within a sac, 
Fig. 198.—Horizontal Section of Ac- < ’ 
tinia through the stomach, show- like the neck of a bottle turned 
iug septa and compartments. . . . 
outside in. I he inner sac, winch 
is the digestive cavity, does not reach the bottom, but 
opens into the general body-cavity. 130 The space between 
these two concentric 
tubes is divided by a 
series of vertical parti¬ 
tions, some of which 
extend from the body- 
wall to the digestive 
sac, but others fall 
short of it. Instead, 
therefore, of the radi¬ 
ating tubes of the Aca- 
lepli, there are radiat¬ 
ing spaces. No mem¬ 
bers of this class are 
. . . .. Fi<». 199.—Actinia expanded, seen from above, 
microscopic. All are showing mouth. 
