238 THE WORLD OF THE SEA. 
parent cylinders; from each of these, twenty minute suckers, or 
prehensile arms, are thrust out, or pulled in, at will. Therefore, 
upon the head of the clio there are no less than 360,000 of these 
beautifully-constructed arms. In the whole extent of nature there 
is no creature which possesses such an organ with which to seize 
its prey. The meanest organ on the most insignificant animal, 
when closely examined, arouses our astonishment and excites our 
enthusiasm ; and again and again observation testifies that there 
is nothing neglected or imperfectly finished in nature. 
Another pteropod—quite as beautiful and remarkable as the 
clio—is the Hyalea tridentata. This species does not possess 
THE TRIDENT HYALAA. THE EDGED HYALA:A. 
(Ayalea tridentata.) (Ayalea limbata.) 
tentacles, but it is clothed in a shell. Its fins are very widely 
expanded; they are painted yellow, with a spot of beautiful violet 
at their base. The upper side of the shell is convex; the under 
side flat ; and the superior part overlaps the lower. In one species 
the shell has something the form of a trident. Its colour is a 
yellow amber, and it is semi-transparent. When the pteropod 
swims, it extends the two wing-like expansions from beneath its 
shell, out of the lateral slits. 
