JELLY-FISH, ETC. 
4§3 
relates that during the first voyage round the world made by the ship Princess 
Louise, a sailor jumped into the sea to capture a large Physalia. As he seized it, 
the animal enveloped him in its long filaments, stinging him so terribly that he 
cried out for help, and was hardly able to swim back to the ship to let himself be 
hoisted up. Severe inflammation and fever followed, and his life was for some 
time despaired of. 
During the Challenger expedition, deep-sea Siphonophora of a remarkable 
kind were brought to light. The most interesting belonged to a new family, the 
Auronectidce. The colony, instead of being a long string of individuals, is here 
thickened and shortened so as to be oval or round. It consists of a hard, 
cartilaginous mass, traversed by a close system of branching canals. The upper 
part of this mass is a large, round, hollow air-bladder ( p in the figure). This 
pneumatophore is surrounded by a 
circle of large, round swimming-bells 
(n), one of which ( l) is modified in 
a remarkable way. It is not, like 
the rest, quite hollow, but is traversed 
by a narrow canal attached to its 
walls by strands of gelatinous tissue. 
The free end of the canal opens out¬ 
ward through a short tube, while its 
attached end enters the great 
bladder of the pneumatophore. This 
specially modified rowing-bell has 
been called the aurophore, since it 
appears to regulate the quantity of 
air in the air-bladder. In order to 
sink to a greater depth, the Steplcalia 
has only to contract its pneumato¬ 
phore, discharging the air through 
the lateral canal. When the animal 
rises, the aurophore probably secretes a gas which fills the pneumatophore again. 
The lower end of the colony is occupied by a large feeding or nutritive polyp, 
and at its sides there are several rows of smaller nutritive polyps (s), each of 
which, at its base, carries a capturing filament ( t ), and at its side grape-like 
clusters of reproductive bodies. 
The Siphonophora, as a rule, require frequent changes of depth. It does not 
appear that exclusively deep-sea forms are to be found in the Mediterranean, but 
that all Siphonophora under certain circumstances and at certain seasons appear 
at the surface. Many pass through their larval development at a great depth, 
and the young Physophora larvae found at the surface in the spring descend to 
greater depths at the commencement of summer, and only return, when their 
metamorphoses are complete, to develop into sexually mature animals. In the 
Physophoridoe we had the different individuals in a long series. I11 the Auronectidce 
we found them arranged in a compact mass; and, lastly, in the Velellida’, the 
body is flattened out to a disc, which is traversed by a system of canals. On 
Stephalia (nat. size). 
