202 
THE OCEAN WORLD. 
of Peron, whose body is globose, scolloped with eight marginal ten* 
tacles, peduncles ending in four leaf-like, furbelowed arms, united at 
the base, having four ovaries, and appendages to the stomach, without 
orifices. 
The Pelagia, as the name implies, belong to the deep sea. P. noc~ 
tiluca has a transparent, glass-like disk, of a reddish-brown colour and 
warty appearance. It is found in the Mediterranean, about the coast 
near Nice, and is still more plentiful on the coast of Sicily, and on the 
African coast. Another species, P. panopyra, is very common in the 
Atlantic and Pacific, between the Tropics. The naturalist Lesson met 
whole banks of them in the equatorial ocean, about the twenty* 
seventh degree north latitude and the twenty-second degree west Ion* 
gitude. During the night, this species emits a brilliant phosphoric 
light, and living individuals, which Lesson succeeded in preserving* 
exhibited great luminosity in the dark. This medusa is remarkable for 
its semi-spherical disk, slightly depressed, umbilicate at the summit, 
a little compressed at the edges, and densely bristling on the surface 
with small elongated warts, but regularly festooned along the edges- 
In colour it is a delicate rose. 
The animals which constitute this class of Zoophytes, and, in former 
times, so curious and so imperfectly known, were designated Polypo- 
medusm, in order to remind us that at one time they were called 
Medusae, and at others ranged among the Polypes. It has, however, 
been recently discovered that, shortly after they issue from the egg, 
these zoophytes show themselves in the form of polypes, and that, at a 
later period, they assume the animal form, to which we give the name 
of medusa. These animals are, then, true proteans : hence the very 
considerable difficulty of studying them— difficulties which have long 
reduced naturalists to despair. Ill veil now then’ history is too obscure 
and too complicated to justify ns in presenting it, except in its general 
features. We shall, therefore, content ourselves here with a descrip' 
tion of the best known species of the class only — those, namely, which 
have particularly attracted the attention of naturalists, and which are, 
at the same time, ot a nature to interest our readers. 
The class of Discophorse may be divided into four orders or families* 
namely : 
I. The Hydkaim:, having single, naked, gelatinous, sub-cylindrical, but very con- 
