HOLOTHUROIDE &. 287 
“ sea-cucumber” expresses with wonderful exactness the shape of the 
animal, and its habitation, the sea; and, again, it would puzzle the 
most learned to explain the word Aolothuria. ‘The body of this 
strange creature presents the form of an elongated and worm-like 
cylinder ; its dimensions are so variable that, while some species are 
only an inch or two in length, others attain thirty and even forty 
inches. In general, the skin of the Holothuria is thick and leathery ; 
it is provided with muscles, and is armed occasionally with small 
projecting hooks or anchors, which enable the creature to hang for a 
few seconds on to foreign bodies. From this coriaceous envelope 
issue ambulacral feet analogous to those described in the sea-urchins 
and sea-stars. 
When we open a Holothuria we find nearly the whole internal 
cavity occupied with little white tubes. We know that the fabulous 
cucumber spoken of in the “ Arabian Nights” was stuffed with pearls 
by the talking-bird. With our poor animal this, alas! is not so. 
These are no pearls, but simple prosaic cecal tubes. The mouth 
opens at the extremity of the body; it forms a sort of funnel, and is 
surrounded like a crown, with an elegant circle of tentacula. In the 
living animal, when it feels itself in security, these tentacles expand 
themselves like the corolla of a flower. When the fisherman seizes a 
Holothuria in the water this crown of tentacles ceases to appear, for 
the animal has the power of withdrawing it quite suddenly, and now 
it resembles nothing so much as a common leech. If, however, it is 
preserved in fresh sea-water, and left in peace—if we treat it, in short, 
with the regard due to its elegant crown of tentacles—this elegant 
ornament will be expanded in all its glory. Immediately below the 
mouth is a muscular pharynx, which is contained in a long intestine, 
with many convolutions, which terminate in the posterior part of the 
body in an orifice whence is thrown from timetto time a little jet of 
water. The terminal portion of the intestinal canal in these animals 
is enlarged, introducing us to a system of numerous tubes which 
branch off into the visceral cavity, receiving the water from without 
while breathing by its posterior extremity; the animal can at will 
fill this reservoir or eject the water, and it is by these alternate 
movements of inspiration and its reverse that it renews the oxygen 
necessary for respiration. The circulation appears to form a com- 
-plete circle, there being no heart or central organ ; but a ring round 
the gullet, from which issue five principal nervous chords, represents 
the nervous system. 
The Holothuria are of separate sexes, and they differ from the sea- 
urchins and star-fishes in this: that the ova are developed in many 
