242 CCELENTERATES ; ACALEI'HS. . 



One of these is the Pcntacriniis caput-nicduscc, of the 

 West Indies, Figure 471. Some of the living Crinoids 

 are free-swimming when adult, and much resemble the 

 Ophiurans. 



In the rocks, in various parts of the United States 

 and in other countries, fossils of the stemmed kinds are 

 exceedingly abundant, showing us that these animals 

 lived in profusion in the old ocean which ages ago 

 covered a large part of our country. And the fossils 

 are so various in form, and so beautiful in pattern and 

 marking, that no words can fitly describe them. The 

 workman in the quarry stops to admire them, and the 

 learned naturalist is fascinated by their beauty, and 

 never grows weary of studying them. They are the 

 gems of the geological collection. 



Of the living free Crinoids, — that is, those without 

 a stem, — one of the best known is called the Ante- 

 don, or Feather Star. When young this, too, has a 

 stem, and looks not very unlike the Medusa's Head, 

 Figure 471 ; but as it grows older it drops from the 

 stem, and lives a free life. 



CCELENTERATES, OR LASSO-THOWERS. 



These radiated animals are cylindrical in form. They 

 have no digestive canal separate from the body wall. 

 All of them have nettle cells, as described below. 



The main kinds are the Jellyfishes including Cteno- 

 phora and Hydroids, and Polyps. 



JELLYFISHES, OR ACALEPHS. 



Of all animals of the sea, perhaps none are more 

 wonderful than these. Their jellylike bodies, curious 



