MEDUSID A. 163 
voracious, and snap up their prey all at one mouthful, without 
dividing it. If their prey resists and disputes with it, the Medusa 
which has seized it holds it fast, and remains motionless, and, without 
a single movement, waits till fatigue has exhausted and killed its 
victim, when it can swallow it in all security. 
In respect to size, the Medusze vary immensely. Some are very 
small, while others attain more than a yard in diameter. Many 
species are phosphorescent during the night. 
Most Medusidz produce an acute pain when they touch the 
human body. The painful sensation produced by this contact is so 
general in this group of animals, that it has determined their desig- 
nation. Until very recently all the animals of the group have been, 
after Cuvier, designated under the name of Acalephe, or sea nettles, 
in order to remind us that the sensation produced is analogous to 
that otcasioned by contact with the stinging leaves of the nettle. 
According to Dicquemare, who made experiments on himself in 
this matter, the sensation produced is very like that occasioned by a 
nettle, but it is more violent, and endures for half an hour. ‘In the 
last moments,” says the abbé, ‘“‘the sensation is such as would be 
produced by reiterated but very weak prickings. A considerable 
pain pervaded all the parts which had been touched, accompanied 
by pustules of a reddish colour with a whitish point.” 
Their organisation is much more complicated than early observers 
were disposed to think it. During many ages naturalists were 
inclined to imagine, with Réaumur, that the Meduse were mere 
masses of organised jelly, or, as it were, of gelatinised water. But 
when Courtant Dumeril tried the experiment of injecting milk into 
their cavities, and saw the liquid penetrating into true vessels, he 
began to comprehend that these very enigmatical beings were werthy 
of further study; and the study of subsequent naturalists, such as 
Cuvier, De Blainville, Ehrenberg, Brandt, Eschscholtz, Sars, Milne- 
Edwards, Forbes, Gosse, and other recent naturalists, have demon- 
strated what richness of structure is concealed under the gelatiniform 
and simple structure to be met with in the Medusz ; at the same 
time they have revealed to us most mysterious and incredible facts 
in connection with their metamorphoses. Among the Medusze 
proper, that is the Gymnophthalmata, we find the genus 2quorea. 4. 
violacea is figured on page 157 (Fig. 52). Of the genera belonging 
to the Steganophthaimata among the most common are Pelagia and 
Chrysaora. In the former genus we find P. noctiluca. In the latter, 
C. Gaudichaudi (Fig. 54), the disc is hemispherical, festooned with 
numerous tentacles, attached to a sac-like stomach, opening by a 
L 2 
