ACALEPH/E. 
219 
a V disappear by turns in the same reg.on, at determinate epochs 
Vernations which depend, no doubt, on the ruling of the winds and 
^rents which carry or lead them. “ The barks which navigate Lake 
•Van meet,” says Fredol, “ at certain periods of the year with nume- 
10118 colonies of a species about the size ot a small melon, nearly 
tra nsparent— 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 
Vddle of the neck. This mouth is rarely unoccupied. Small molluscs, 
JVug crustaceans, and worms, form their ordinary food. In spite of 
' 10lr shape, they are most voracious, and snap up their prey all at one 
"""dlifid, without div idin g it. If then prey resists and disputes with 
lt > Ve Medusa which has seized it holds last, and remains motionless, 
JH without a single movement, waits till fatigue has exhausted and 
cd its victim, when it can swallow it in all security. 
V respect to size, the Medusas vary immensely. Some are very 
s, °all, while others attain more than a yard in diameter. Many 
T e cies are phosphorescent dming the night. 
, ito st Medusadae produce an acute pain when they touch the human 
'%• The painful sensation produced by this contact is so general in 
lis group of animals, that it has determined their designation. Until 
J ei 7 recently all the animals of the group have been, after Cuvier, 
Vgnated under the name of Acalephae, or sea nettles, in older to 
^ ttfind us that the sensation produced is analogous to that occasioned 
^ contact with the stinging leaves of the nettle. 
According to Dicquemare, who made experiments on himself in 
t ls 1 Matter, the sensation produced is very like that occasioned by a 
I but it is more violent, and endures for half an hour. “ In the 
5* foments,” says the abbe, “ the sensation is such as would be pro- 
Uc V hy reiterated but very weak prickings. A considerable pain 
, erva ded all the parts which had been touched, accompanied by pus- 
08 the same colour, with a whitish point.” “ The sea-bladder, 
s Father Feuillee, “occasions me, on touching it, a sudden and 
P ai11 , accompanied with convulsions.” „ 
t Turing the first voyage of the Princess Louise round the world,” 
0 Tiote Fredol, “Meyen remarked a magnificent physalia, which 
U " 1 near the ship. A young sailor leapt naked mto the sea, to 
till. 
