LIFE IN THE OCEAN. 59 
‘a young conger eel, which has sought refuge there ; while the pools, 
left here and there by the retiring tide are dragged by nets of very 
small mesh, in which the smaller crustacea, molluscs, and small fish 
are secured,” 
In the Mediterranean and other inland seas, where the tide is 
almost inappreciable, there will be found to exist a great number of 
animals and Algze belonging to the deep sea, which the waves or 
currents very rarely leave upon the sea-shore. There are others, again, 
so fugitive, or which attach themselves so firmly to the rocks, that 
we can watch them only in their habitats. It is necessary to study 
them floating on the surface of the waves, or in their mysterious 
retirements. Hence it is often necessary that naturalists should 
study the living productions of the sea, both on the bosom of the 
ocean as well as on the sea-shore. 
The means generally employed for scraping the sea-bottom is a 
dredge-net, or other suitable engine. In a voyage which Milne- 
Edwards made round the coast of Sicily, he formed the idea of 
employing an apparatus invented by Colonel Paulin, which consisted 
of a metallic casque provided with a visor of glass, and consequently 
transparent, which was fixed round the neck by means of a copper 
collar made water-tight by stuffing—a diving-bell, in short, in miniature. 
It communicated with an air-pump by means of a flexible tube. 
Four men were employed in serving the pump, two working while 
the other two rested themselves. Other men held the extremity of a 
rope, which was passed over a pulley attached at a higher elevation, 
and enabled them to hoist up the diver with the necessary rapidity 
in case of emergency. A vigilant observer held in his hand a small 
signal cord. The immersion of the diver was facilitated by heavy 
leaden shoes, which assisted him at the same time to maintain his ver- 
tical position at the bottom. Milne-Edwards made the descent with 
this apparatus in three fathoms water with perfect success. He was 
thus enabled to study, in their most hidden and most inaccessible 
retreats, the radiate animals, molluscs, crustaceans, and annelids, and 
by his descriptions he has contributed most essentially to our know- 
ledge of the manners and mode of development of certain m- 
habitants of the sea, whose sojourn and habits would have seemed 
to sequestrate them for ever from our observation. 
Another and easier mode of studying the living creatures 
sheltered by the sea was first suggested by M. Charles des Moulins, 
of Bordeaux, in 1830. The aguarium, which is a tank or large 
water-tight vessel charged with fresh or salt water, according to the 
