SEA ANEMONES. 203 
where the vast freshwater current of the Mississippi debouches into 
the sea, they are unknown. It is principally on the north coast and 
upon the eastern flanks of the chain of West Indian Islands that the 
coral reefs show themselves in these regions. 
Tue ACTINIDA. 
Here we leave the group of polyps which form united families. 
The Sea Anemones, of which the genus Actinia is the type, consist of 
Zoantharia, which produce no true polypidom, that is to say, of 
polyps whose integument remains always soft, and in whose interior 
no calcareous ‘plates are produced. This order is usually divided 
into two groups—that in which the base is adherent at pleasure, as in 
Actinia, and that in which the base is not adherent, as in //panthus. 
The modern aquarium enables the spectator to witness many 
wonderful sights. Adherent against the transparent crystal walls 
of the basin, he observes living creatures of the most_brilliant shades 
of colour, and more resembling flowers than animals. Supported 
by a_base- and cylindrical stem, he sees them terminate like the 
corolla of a flower, as in the petals of the anemone: these are the 
animals we call Sea Anemones—curious creatures, which, as all per- 
sons familiar with the sea-shore may have observed, are at one time 
seen suspended from the rocks, and again buried at the bottom of 
the sea. These charming and timid creatures are also called Actinia, 
as indicating their disposition to form rays or stars, from the Greek 
auris, & Tray. 
The body of these animals is cylindrical in form, terminating 
beneath in a muscular disc, which is generally large and distinct, 
enabling them to cling vigorously to foreign bodies. It terminates 
above in an upper disc, bearing many rows of tentacles, which differ 
from each other only in their size. These tentacles are sometimes 
decorated with brilliant colours, forming a species of collar, consisting 
of contractile and often retractile tubes, pierced at their points with 
an orifice, whence issue jets of water, which are ejected at the will of 
the animal. Arranged in circles, they are distributed with perfect 
regularity round a central mouth. These are their arms. 
The mouth of the Sea Anemone opens among the tentacles. 
Oval in form, it communicates by means of a short tube with a 
stomach, broad and short, which descends vertically, and abuts by a 
large opening on the visceral cavity, the interior of which is divided 
into little chambers. These chambers are not all of the same dimen- 
sions ; in parting from the cylindrical walls of the body, they advance, 
