Q49 COMPARATIVE ZOOLOGY. 
single life, and is capable of a slow locomotion. Muscular 
fibres run around the body, and others cross these at right 
Fic. 195.—A Ctenophore (Pleu- 
robrachia pileus); natural 
size. 
angles. The tentacles, which often 
number over 200, and the partitions, 
which are in reality double, are in 
multiples of six. At night or when 
alarmed, the tentacles are drawn in, 
and the aperture firmly closed, so 
that the animal looks like a round- 
ed lump of fleshy substance plaster- 
ed on the rock. It feeds on Crabs 
and Mollusks. It abounds on ey- 
ery shore, especially of tropical seas. 
The size varies from one-eighth of 
an inch to a foot in aanteter 
The Ctenophora (as the Pleuro- 
brachia, Cestum, and Beroé) likewise secrete no hard de- 
posit. They are transparent and gelatinous, swimming 
on the ocean by means of eight 
bands of comb-like fringes, which 
work like paddles. The body is 
not contractile as in the Jelly- 
fishes. They are considered the 
highest of Ccelenterates, having a 
complex nutritive apparatus and 
a definite nervous system. 
2. Coral Polyps.—The majori- 
ty of Anthozoa secrete a calcare- 
ous or horny frame-work called 
“coral.” With few exceptions, 
they are fixed and composite, liy- 
ing in colonies formed by a con- 
tinuous process of budding. Their 
ce t Mi een 
uubin 
Fra. 196.—Organ-pipe Coral (Tubi- 
pora musica). Indian Ocean. 
structures take a variety of shapes: often dome-like, but 
more frequently imitating shrubbery and clusters of leaves. 
