INVERTEBRATE ANIMALS. 47 



(Arthropoda), subsequently of a type with an endo- 

 skeleton (Vertebrata), by degrees consigning their 

 combined energies to be under the superintendence, 

 first of a cephalic ganglion, at length of a brain. 



Class ECHINODERMATA. 



sx'ivoc, the hedgehog; ^Bpfji,a, the skin. 



The general arrangement of the groups in thi Clans 

 is in accordance with the classification adopted 

 by MM. Dujardin and Hupe, in " Histoire 

 Naturelle des Zoophytes Echinodermes." {Suites a 

 Buffon. Paris, 1862). 



Sab- Class CRINOIDA. 



Kp~ivog, !i lily ; e'ttioc, form 



Body of the animal, during the whole or a portion of its 

 existence, attached to the sea-bottom by a jointed and 

 flexible stalk. 



Group 133.— Orders CYSTOIDEA, BLASTOIDEA, and 

 CRINOIDEA in part. The Cystoidea, earliest of the 

 Echinoderms, attained their maximum in the Lower 

 Silurian. They were closely followed by the Blastoidea, 

 or Pentrcmites, and the Crinoidca, or Stone-Lilies : the 

 latter alone survived, though in diminished numbers, 

 the Palaeozoic age. Estimated number of species, 140, 

 M. Dujardin. 



Group 134.— Family PENTACRINID^ (D'Orbiguy). The 

 beautiful Pentacrinus Midleri is one of the few living 

 forms which very closely connect the animal life of the 

 present age with that of ages immeasurably remote. 

 Living in the deeper waters of the Caribbean Sea, it has 



