106 STARFISH GALLERY. 
THE STARFISH GALLERY 
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In the Starfish Gallery is exhibited a series of the animals 
belonging to the class Echinoderma ; of these the Starfishes are the 
best known, while others are the Sea-Lilies, Sea-Urchins, and Sea- 
Cucumbers or Sea-Slugs. 
A small collection of various kinds of Worms is also exhibited in 
this Gallery (Wall-cases I.-IIL). 
ECHINODERMA. 
Six table-cases contain the dried Echinoderms arranged in 
systematic order. The seventh is devoted to preparations, models, 
and figures illustrative of the structure and life-history of various 
members of the group. 
An inspection of that Case and the accompanying woodcuts will 
make clear the distinctive characters of the Echinoderma. Unlike 
that of a Crayfish or a Mussel, the body does not appear to be divided 
into two equal or symmetrical halves, though it really is ; this is due 
to the possession of a number of rays, of which there are ordinarily 
five. The skin is strengthened by the deposition in it of carbonate 
of lime, which may be in the form of continuous plates or bars, 
or of separate scattered spicules. A series of tube-feet or suckers 
(podia) are generally developed along each ray, and these are 
supplied by a system of water-vessels peculiar to Starfish and their 
allies. These rays are often called " ambulacra" 
In the body of the Starfish (Fig. 3) the arms are seen to be 
continuous with the disk and to contain portions or prolongations 
of the chief organs. The middle of the arm is occupied by two 
rows of hard pieces (ambulacral ossicles), the fellows of which make 
an open angle with each other, and so form an open ambulacral 
