In the same way,
if we place them in the same attitude, we shall see that the long,
straight rows of suckers along the length of the Holothurian, and the
arching zones of suckers on the spherical body of the Sea-Urchin, and
the furrows with the suckers protruding from them along the arms of
the Star-Fish and Ophiuran, and the radiating series of pores from the
oral opening in the Crinoid are one and the same thing in all, only
altered somewhat in their relative proportion and extent. Around the
oral opening of the Holothurian there are appendages capable of the
most extraordinary changes, which seem at first to be peculiar to these
animals, and to have no affinity with any corresponding feature in the
same Class. But a closer investigation has shown them to be only
modifications of the locomotive suckers of the Star-Fish and
Sea-Urchin, but ramifying to such an extent as to assume the form of
branching feelers. The little tufts projecting from the oral side in
the Sea-Urchins, described as gills, are another form of the same kind
of appendage.
The Holothurians have not the hard, brittle surface of the other
Echinoderms; on the contrary, their envelope is tough and leathery,
capable of great contraction and dilatation.
Pages:
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283