376 Some Account of the Meduse 
umbrella form with the horizon an angle more or Jess ob- 
tuse ; and in this new situation, the direction of the shock 
being oblique, like that of the resistance, the animal is it- 
self repelled, and moves in this last direction. When at the 
surface of the water, the vertical position can uo longer have 
any effect but to keep the zoophyte in its place; but in 
order to change it, it must return to the oblique position. 
Tt is in fact in this last way that the whole of the meduse, 
whose bodies are gelatinous and orbicular, swim on the 
surface of the water; their umbrella is never on the line of 
the horizon, except when they are in a state of rest. 
The mechanism to which the equore have recourse in 
order to redescend to the bottom of the sea, is still more 
simple than the various motions which we have described. 
Their substance being in fact of a greater specific gravity 
than that of sea-water, it is sufficient for them to contract 
strongly in order to sink by their own weight. In certain 
cases, with a view to precipitate their descent, they turn 
round in such a manner as. to make the lower part of the 
umbrella uppermost; and in this position they execute the 
same motions as when they rise to the surface. 
Methods of discovering and seizing their prey.—All these 
evolutions of the equoree have for their essential object 
the seizing of their food; and although less favoured in 
this respect than the meduse which are provided with 
arms, they have nevertheless received from nature means 
as various and powerful for assuring themselves of the suc- 
cess of their effects. The filiform teutacula, of various 
Jengths and more or less numerous, which fringe the um- 
breila, are endowed with the most exquisite sensibility : al- 
ways in full activity around the animal, they eagerly seize 
the prey which they stand in need of: they wrap their ten- 
tacula around it, and carry it towards the aperture of the 
stomach, which dilates while the, fringes or filaments 
around it attack the victim, and it Is speedily engulfed in 
the fatal cavity. 
To these prehensile weapons some species of equoreze 
perhaps add that burning causticity which distinguishes 
several other medusz, but none of those observed by us 
appeared to enjoy this remarkable property. 
The food of the equoree is probably in a great mea- 
sure composed of those myriads of gelatinous animalcules 
which float on the ocean ; and the investigation of which, 
although but recently begun, has already unveiled so many 
wonders. and thrown to such a distance the boundaries of 
animal existence and organization; the amphicurta equo- 
rea, 
