234 
TIIE 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 Medusa: originating by budding in the case of those reproductive 
individuals, constitute the sexual state of the Yilellae. 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-sexuab 
and in it they form swimming colonies, under the special designation 
of Vildlee. 
The Vilellm, so called by Lamarck, are found widely diffused in the 
seas of Europe, Asia, America, and Australia. One species, V. fimbosa, 
is often taken on the southern coasts of England. The animals arc 
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 Iiataria and Porjnta. 
The Kataria 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. I)e Blainville was inclined to consider the 
very small animals which Eschscholtz termed Eatarias as young 
and undeveloped VilelJss. M. Vogt doubts not that the Eatarise af° 
young Vilellm 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. Those Eatarias are engendered, according t° 
Vogt, by the naked-eyed Medusae born of the Vilellm, and owe their 
existence to the eggs produced by these Medusae. 
The Porpitae constitute, like the Vilellae, colonies of floating animal 9 
furnished with a cartilaginous, horizontal, and rounded skeleton, hut 
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 
stria? ; the upper surface being covered by a delicate membrane only* 
The body is concave below; the under surface is furnished with 9 
