CLASS IV. 

 ECHINODERMS (ECHINODERMATA) 1 . 



THE name JEchmodermata was used by J. T. KLEIN rather 

 more than a century ago, to denote the shells of the sea-urchins, 

 called Echini. 'E^II/OS, with the Greeks, denoted both an urchin 

 and a sea-urchin. Afterwards BRUGUIERES gave the name of 

 Echinodermata to a division of the animal kingdom that comprised 

 at once the sea-urchins and the star-fishes. CUVIER retained that 

 name for this division, but added to it animals having a coriaceous 

 skin without spines or quills. Although the name is no longer 

 applicable to all the species of this class, yet the class itself must 

 be looked upon as an extremely natural division of the Animal 

 Kingdom. These animals are distinguished by an intestinal canal 

 hanging free in the cavity of the body by single threads or mem- 

 branes, usually long and tortuous, or provided with lateral append- 

 ages if it be short: blood vessels and respiratory organs are present; 

 the genital organs, in both sexes of the same external form, are 

 without any special apparatus for copulation ; the fertilisation being 



1 Consult on this class : 



L. AGASSIZ, Monographies d' Echinodermes vivans etfossiles. Neuchcatel, 1838 and 

 fols. 4to. (The parts thus far have reference only to certain figures of Echini. The 

 fourth, published in 1842, contains the anatomical description of Echinus lividus, by 

 VALENTIN.) 



E. FORBES, A History of British Star-fishes and other animals of the class Echino- 

 dermata. Illustrated by woodcuts. London, 1841, 8vo. 



A capital work on the anatomy of this class is : 



F. TIEDEMANN, Anatomic der Rohren-Holothurie, des pomeranz-farbigen Seestems 

 und Stein-Seeigels. Landshut, 1816, folio; a prize Essay crowned by the French 

 Institut in 1812. 



W. SHARPEY, The article Echinodermata in TODD'S Cyclopaedia of Anat. and Phy- 

 siolog. n. pp. 30 46 (1836). 



J. MUELLER, Ueber den allgemeine Plan der Entwickelung der Echinodermen. Mit 8 

 Kupfertaf. Berlin, 1853, 4to, and previous papers in the Abh. d. AJcad. der Wissen- 

 schaf. zu Berlin 1849, J 85O. 



G. L. DUVERNOY, Mem. sur V Analogic de Composition et sur quelques points de 

 r Organisation des Echinoderms. Mem. de I'Acad. des Sciences, XX. Paris, 1848. 



