206 HOMOLOGIES. 



cation of thek structure, with the succession of 

 the fossil ones. Of the five Orders, Beches-de-Mer, 

 Sea-Urchins, Star-Fishes, Ophiurans, and Cri- 

 noids, or, to name them all according to their 

 scientific nomenclature, Holothurians, Echinoids, 

 Asterioids, Ophiurans, and Crinoids, the last- 

 named are lowest in structure and earliest in 

 time. Cuvier was the first naturalist who de- 

 tected the true nature of the Crinoids, and 

 placed them where they belong in the classifica- 

 tion of the Animal Kingdom. They had been 

 observed before, and long and laborious investi- 

 gations had been undertaken upon them, but 

 they were especially baffling to the student, be- 

 cause they were known only in the fossil condi- 

 tion from incomplete specimens ; and though 

 they still have their representatives among the 

 type of Echinoderms as it exists at present, yet, 

 partly owing to the rarity of the living specimens 

 and partly to the imperfect condition of the fossil 

 ones, the relation between them was not recog- 

 nized. The errors about them certainly did not 

 arise from any want of interest in the subject 

 among naturalists, for no less than three hundred 

 and eighty authors have published their investi- 

 gations upon the Crinoids, and the books that 

 have been printed about these animals, many of 

 which were written long before their animal na- 

 ture was suspected, would furnish a library in 

 themselves. 



