CORALLINES. 
147 
longitudinal lines or septa, stretching between the membrane and the 
central stomach, which divide the intermediate space into an equal 
number of compartments. These lines not only extend to the base of 
the tentacula, but rim across the anal disk, and terminate in a central 
mouth. The tentacula are short, obtuse, ciliate on the margins, and 
strengthened at their roots by numerous crystalline spicuhe. The 
polype cells are oval, placed just under the skin, and are the termi- 
nating points of certain long canals which traverse the whole polypier. 
The polypes, which are distributed oyer the whole surface, can with- 
draw into the cavities ; they are, besides, of an extremely vital sensibi- 
lity : the least shock impresses itself on the tentacula, the impulse of 
a wave even producing contraction; in response, the animal, which 
is well developed, sallies out perceptibly, hut immediately retires again 
to hide itself in the cell. 
We find on the coast, in the Channel, and in the North Sea, 
Alcyonium cliyituluvi, the mass of which is of a reddish white, 
ferruginous, or orange ; A. stollutum, found on the shores of the 
Mediterranean, is expanded in its upper part, narrow towards its base, 
very rough on the surface, and rose-coloured ; A. palmatum is cylin- 
drical, branching at the summit, of a deep red, except at the base, 
where it is yellow : this is met with in the Mediterranean. 
We may note as a type, altogether different from any yet touched 
upon, the Nephtys, in which the polypier is a coriaceous tissue bristling 
with spicule© over its whole surface. In N. Chabroli, the polypier is 
s fiuat, with thick spreading arms covered with lobiliform branches, the 
tubercular polypier of which are columnar and obtuse, the sicula green, 
a ud the tentacula of the polypes yellow. 
“ On a cursory view,” says Dr. Johnston, “the polypodium of the 
three families embraced appear very dissimilar, and accordingly, by 
many recent authors, they have been scattered over the class, and 
placed widely asunder. The affinity between them, however, is gene 
r ally acknowledged, and had been distinctly perceived by some of the 
earliest zoophytologists. Thus Bob ad sell found so much in common 
m the typical pennatuhe and a species of Aleyonium, that ho has not 
hesitated to describe them as members of the same genus; and, 
although the more systematic character of Pallas prevented him tiom 
falling into this error, if error it can be called, he did not the less 
recognise the relationship between the genera or families. Pallas also 
