CLASS III. CTENOPHORA. 



631 



ORDER 2. CHONDROGRADAo 



These animals are called Chondroc/rada 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 beinw their 

 prevailing color. In the genus Porjnta, 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 VelcUa, 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. 



Class III. CTEIVOPIIORA, 



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 o^ cilia. 



The Beroklce^ 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 CalUaniridce are distinguished from the Beroidaj by the small size of the stomach and 

 mouth, and by the possession of filamentous tentacles. The Cydipiie, 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 

 is the Venus' Girdle, Cesium Veneris, 



THE CYDIPPE, FOEMERLX CALLED THE BEROE PILEUS. 



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. 



