ECHINODERMATA.—VERMES. 
263 
ing calcareous granules. One end, the head, is abruptly 
terminated, and lias a simple aperture for a mouth, en¬ 
circled with feathery tentacles. There are usually five 
longitudinal rows of ambulacral suckers, but only three 
are used for locomotion, of which one is more developed 
than the rest. The mouth opens into a pharynx leading 
to a long intestinal canal. Holothurians have the singular 
power of ejecting most of their internal organs, surviving 
Fig. 215.—Sea-slugs ( Holothuria ). 
for some time the loss of these essential parts, and after¬ 
wards reproducing them. They occur on nearly every 
coast, especially in tropical waters, where they sometimes 
attain the length of three or four feet. As found on the 
beach after a storm, or when the tide is out, they are 
leathery lumps, of a reddish, brownish, or yellowish color. 
They may be likened to a Sea-urchin devoid of a shell, 
and long drawn out, with the axis horizontal, instead of 
vertical. 
Subkingdom V. —Vermes. 
The Vermes, 136 or Worms, form the lowest subkingdom 
of the bilaterally symmetrical animals. The group in¬ 
cludes animals very different in form and rank, and the 
different classes are widely separated from each other. 
