THE CEPHALOUS MOLLUSKS. 229 
with their branches tattered and torn, and some even completely 
off. However, they have the power to reproduce their injured 
organs. Mr. Rymer Jones watched one of these mollusks replace 
a damaged tentacle in a fortnight. . 
These curious creatures are generally about two inches long; 
their body is yellow, and the respiratory branches pink, passing 
to flesh-colour at their tips ; towards the tail their colour deepens 
into purple. They have two pairs of horns—the anterior ones are 
slender and flexible, the posterior are much thicker and of a red 
hue. Altogether, this mollusk is beautifully coloured, and presents 
a delicate arrangement of tints seldom met with. 
We shall but allude to another of this class. The A mphorina 
Alberti has a long, thin, tapering body. Its head is large, and 
rises higher than the surface of the back; from the head 
project two pairs of horns. The hinder are longer and altogether 
larger than the first ones, and all of them point forward like 
the ears of a hare when listening to a noise in advance; but the 
most peculiar feature of the animal are the branchial appendages, 
which differ from those of every other mollusk. These are four 
enormous, ovoid bodies attached to the back, and between these 
are eight others, much less, and of a fusiform shape, which are 
arranged in two ranks, one on each side the central line of the back. 
The animal’s body, indeed, is like a slender branch, from which 
hangs a bunch of large-sized fruit, only the fruit stands upright on 
the stalk. The general colour is grey, the horns and respiratory 
prominences being tipped with yellow, and down the dorsal line 
are spots of yellow. 
The cephalous mollusks which are covered have a shell in one 
piece, and are therefore called Univalves. In some of the species 
the mouth of the shell is shut by an oferculum, a little door, which 
may in some sense be regarded as a second valve. The Verita 
offers an example of this construction. The shells of the univalves 
are usually spiral; the reason of this leads us to the very interesting 
explanation of their development. When the egg of the mollusk is 
dropped, if it be examined under the microscope, it is seen to be 
constructed like a bird’s egg; it has a yolk, which is not, however, 
yellow, but grey. This is surrounded by albumen, the white of the 
