STAR-FISHES. 35 
r, that encircles the mouth ; here it flows into tubes that 
branch into each ray, then into numerous sacs, or am- 
pulle, vv, that have long extensions provided with suck- 
ers. By the contraction of the sacs, water fills the exten- 
sions that penetrate the four rows of holes, and they ap- 
pear as feet, suckers, or locomotive organs, ¢7. 
Class I.—Crino1ps (Lily-form). 
Eight living genera of these forms are known. One 
of the most beautiful, the Pentacrinus, is found in deep 
water off the West In- 
dia Islands. They may 
be described as inverted 
star-fishes growing on 
stems. Some are always 
fastened to the bottom 
(Fig. 31), while others 
break off when attaining 
a mature growth and 
lead a wandering life, 
as the Antedon. In the 
Pentacrinus the stem is 
about a foot long, resem- 
bling pentagonal but- Fie oop Sandiatee, 
tons piled one upon 
another, sending off at intervals short whorls of branches 
that are jointed in a similar way. The stem is rooted in 
the mud, while the animal is cup-shaped, presenting the 
appearance of a bunch of rich, waving plumes. These 
are the arms, arranged about the mouth, closing over it, 
or spreading out at will. The Crinoid (Aztedon) is found 
in the Gulf of Maine. They multiply by eggs, that pass 
through several complex changes before assuming the 
parent form. 
