CLASS III. CTENOPHORA. 
631 
ORDER 2. CHONDEOGRADA. 
These animals are called Chondrograda from the circumstance that the circular or oval disc, 
of which their body is composed, is supported upon a somewhat cartilaginous plate, which some- 
times even contains a calcareous deposit; the lower surface of this disc is furnished with cirri, 
some of which are tubular. Many of these creatures are exceedingly beautiful, blue being their 
prevailing color. In the genus Porpita, one species of which is found in the Mediterranean, the 
disc is surrounded by a beautiful fringe of tentacles ; but the most remarkable structure is pre- 
sented by the Velella, in which an oblique upright crest is developed upon the upper surface of 
the disc, serving as a sort of sail to waft the little mariner from place to place. One species of this 
genus is found on the coasts of Ireland. 
€l^§s III. €TE]\OPHORA, 
THE CTDIPPE, FORMERLY CALLED THE BEROS PILEUS. 
"We now come to a class of animals, the real nature of which is still to be made out. They 
are gelatinous, transparent creatures, generally of 
an oval form, enabled to swim freely by the action 
of variously-arranged rows of cilia. 
The Beroidce, which form the first family, may 
almost be said to possess no true stomach, the body 
being so formed as to inclose a great cavity, of 
which the hinder portion serves as a digestive or- 
gan. When the animals have much food in this cav- 
ity, they constrict the middle of the body so as to 
prevent any of it from escaping. The body is oval 
or roundish, with eight rows of cilia running from 
one end to the other. The mouth is large, and 
opens and shuts with facility ; it is generally held 
open when the creature is in motion. The tentacles are wanting in this family. The species are 
gelatinous, and at night shine like lamps suspended in the water 
The GallianiridcB are distinguished from the Beroidae by the small size of the stomach and 
mouth, and by the possession of filamentous tentacles. The Cydippe^ formerly called Beroe Pileus, 
is now referred to this family , it has a globular body, with two long ciliated appendages. But 
the most singular of these animals 
Liuai^i^^^ 
is the Venus' Girdle, Cestum Veneris^ 
which inhabits the Mediterranean, and 
which at first sight would be taken for 
any thing rather than a near relation of 
the little globular Cydippe. In this curi- 
ous creature the sides of the body are pro- 
duced into a long ribbon, which some- 
times attains the length of four or five 
feet; the mouth and digestive organs 
being, however, confined to their original 
position in the middle of the body. This 
animal is one of the most beautiful in- 
habitants of the ocean. When in motion, 
its waving cilia, which are placed along 
the margins of the body, glitter with all the tints of the rainbow ; at night it appears like a long 
waving flame in the water. 
VENUS' GIRDLE. 
