MEDUSID^. 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 Medusae vary immensely. Some are very 

 small, while others attain more than a yard in diameter. Many 

 species are phosphorescent during the night. 



Most Medusid^ 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 Acalephje, or sea nettles, 

 in order to remind us that the sensation produced is analogous to 

 that occasioned 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 abbe', "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 Reaumur, that the Medusse 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 worthy 

 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 Medusae ; at the same 

 time they have revealed to us most mysterious and incredible facts 

 in connection with their metamorphoses. Among the Medusae 

 proper, that is the Gymnophthalmata, we find the genus ALquorca. ^^. 

 violacca is figured on page 157 (Fig. 52). Of the genera belonging 

 to the Steganophthalmata among the most common are Pelagia and 

 Chrysaora- In the former genus we find P. ?ioctiluca. In the latter, 

 C. Gaudichandi (Fig. 54), the disc is hemispherical, festooned with 

 numerous tentacles, attached to a sac-like stomach, opening by a 



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