the fifth and last room, a compartment of the northern zoological
gallery. In this room he will find the wall cases devoted to

CARTILAGINOUS FISHES.

Many of the specimens of this division are placed on the top of the
wall cases, being too large to be placed inside the cases. The
Cartilaginous fishes here brought together include the varieties of
the ray; torpedos; and sharks. At the western extremity of this room
the visitor should terminate the onward course of his first visit,
and, remembering that the table cases of the northern and eastern
galleries through which he has passed, remain to be examined on his
way back to the grand staircase, should begin to retrace his steps,
confining his attention, as he returns, to the table cases placed in
the central space of the rooms through which his way lies. He should
now therefore face the east, and return, in the northern zoological
gallery towards its eastern extremity. The table cases deposited in
the room with the cartilaginous fish are covered with

SPONGES

of different kinds. It will be interesting to the visitor to know
something of the natural history of the sponge. It has been
ascertained, beyond a doubt, that the sponge is an animal that sucks
in its food and excretes its superfluities; that certain of its pores
imbibe, while others exude; and that according to the relative
positions of the two distinct sets of pores, is the shape of the
sponge determined. In a natural state, as it is found in the
Mediterranean, the sponge is surrounded with a thick glutinous matter,
which is its vital part; like coral, it is a zoophyte: it propagates