BOOM XI.^ 
NATURAL HISTORY. 
57 
vertebrated animals. Their body is long, slender, and 
cylindrical, ending in a circular mouth, and destitute of 
pectoral and ventral fins. The true Lamprey ( Petromyzon ) 
has seven branchial openings, whence their vulgar name 
Seven Eyes, and the skin under the tail forms a kind of 
fin. Their mouth is armed with teeth. 
The Gastrobranchus ( Gastrobranchus) differs from the 
Lamprey, by the tongue only being armed with teeth, like 
the Lobworms. These animals emit such a quantity of 
mucus through the pores of the lateral lines, that it con¬ 
verts the water in which it is placed into a jelly. 
Cases No. 9—23 contain Fish preserved in spirits. 
The Table Cases in the centre of the room contain the 
continuation of the collection of Radiated animals, arranged 
according toDe Blainville*. All the Sea Jellies, ( Arach - 
nodermata ,) except Velella and Porpita, (Case 1,) being 
soft, and destitute of any hard part, are incapable of 
being preserved in a dry state. 
The stellated corals, which the Zoantharise, or Animal 
Flowers form, to protect their soft and delicate bodies, are 
generally attached to marine substances, but some of the 
naked species have the power of locomotion. 
The Sea Anemones, the Lucernariae, and the common 
fresh-water Polypus are naked, soft and very contractile, 
and for that reason cannot be preserved in a dry state,— 
consequently they form no part of this collection. 
The Zoanthi resemble the preceding, but the body is 
protected by a hard, coriaceous case into which it contracts 
when at rest. Most of these sheaths are united together 
by a common base, varying in form in the different genera. 
Most of the Zoanthariae form a calcareous covering, 
called coral, into which they can withdraw themselves 
from external danger. This coral consists of a congeries of 
cells, the habitations of the animals, which are formed 
of laminae radiating from a centre, so as to give the cavity 
a stelliform appearance. Corals are generally attached to 
marine bodies during the whole of their growth, but some 
few, as the Sea Mushroom ( Fungio ), and the Sea Slug 
(Polyphy Ilia), only when young, and by a short stem ; as 
the coral enlarges, the crown separates from the stem by a 
natural absorption, and, at length, is left quite free. 
' * Diet, des Sc. Nat. Art. Zoophytes. 
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