ACALEPH2E. 217 



alternations which depend, no doubt, on the ruling of the winds and 

 currents which carry or lead them. " The barks which navigate Lake 

 Thau meet," says Fredol, " at certain periods of the year with nume- 

 rous colonies of a species about the size of a small melon, nearly 

 transparent whitish, like water when it is mixed with a shade of 

 aniseed. One would be tempted to take these animals at first for a 

 collection of floating muslin bonnets." 



The Medusae are furnished with a mouth placed habitually in the 

 middle of the neck. This mouth is rarely unoccupied. Small molluscs, 

 young crustaceans, and worms, form their ordinary food. In spite of 

 their shape, they are most 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 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 spe- 

 cies are phosphorescent during the night. 



Most Medusadae 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 designation. Until 

 very recently all the animals of the group have been, after Cuvier, 

 designated under the name of Acalephae, 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 pro- 

 duced by reiterated but very weak prickings. A considerable pain 

 pervaded all the parts which had been touched, accompanied by pus- 

 tules of the same colour, with a whitish point." " The sea-bladder," 

 says Father Feuillee, " occasions me, on touching it, a sudden and 

 severe pain, accompanied with convulsions." 



" During the first voyage of the Princess Louise round the world," 

 to quote Fredol, " Meyen remarked a magnificent physalia, which 

 passed near the ship. A young sailor leaped naked into the sea, to 

 seize the animal. Swimming towards it, he seized it ; the creature 



