232 THE OCEAN WORLD. 



contractile. Nevertheless, they have considerable resemblance to the 

 corolla of a hyacinth. 



These reproductive individuals are, then, at the same time nurses. 

 The Medusas originating by budding in the case of those reproductive 

 individuals, constitute the sexual state of the VilellaB. They exist, in 

 short, in two alternate states : the one sexual, producing eggs ; in this 

 state they are isolated individuals of the Medusadae, which never group 

 themselves or form colonies : the other aggregate state is non-sexual, 

 and in it they form swimming colonies, under the special designation 

 of Vfle&B. 



The Vilellae, so called by Lamarck, are found widely diffused in the 

 seas of Europe, Asia, America, and Australia. One species, V. limbosa, 

 is often taken on the southern coast of England. The animals are 

 also met with far at sea, and often huddled together in considerable 

 masses, old and young together. 



Such is a brief account of the strange facts to which the careful 

 study of the lower class of marine animals initiates us. Naturalists 

 range along with them the Eataria and Porpita. 



The Eataria have the body oval or circular, sustained by a com- 

 pressed sub -cartilaginous framework, much elevated, having a muscu- 

 lar, movable, longitudinal crest below, and provided in the middle 

 with a free proboscidiform stomach and a single row of marginal 

 tentacular suckers. De Blainville was inclined to consider the very 

 small animals which Eschscholtz termed Batariae as young and 

 undeveloped Vilellse. M. Yogt doubts not that the Batariae are 

 young Vilellae which have acquired, by little and little, the elliptical 

 form, but that the limb is only furnished at a later period to the re- 

 productive individuals. These Batarise are engendered, according to 

 Yogt, by the naked-eyed Medusae born of the Yilellae, and owe their 

 existence to the eggs produced by these Medusae. 



The Porpitae constitute, like the Yilellae, colonies of floating animals 

 furnished with a cartilaginous, horizontal, and rounded skeleton, but 

 they are destitute of crest or veil. The body is circular and depressed, 

 slightly convex above, with an internal circular cartilaginous support, 

 having the surface marked by concentric striae crossing other radiating 

 striae, the upper surface being covered by a delicate membrane only. 

 The body is concave below ; the under surface is furnished with a 



