ECHINODERMATA. 



145 



Fig. 63. 



commencement of this change is perceptible : instead of being com- 

 posed of hard, calcareous pieces, the integuments of the body now 

 become soft and irritable, a few thin laminae of earthy matter 

 around the mouth being the only vestiges of the shell and the 

 spines, of course, are no longer met with ; the suckers, however, 

 remain, and, when protruded through innumerable apertures dis- 

 tributed over the surface of the body, 

 they still form the principal instruments 

 of progression. 



(186.) Fistularidx.At length, in 

 the last division of the class, even the loco- 

 motive suckers are lost, and the only ex- ^ 

 ternal resemblance left between the now 

 worm-like body and the forms above 

 enumerated is met with in the radiating 

 tentacula which surround the mouth. 

 The apodous Echinodermata, " Echino- 

 dermes sans pieds," of Cuvier have 

 indeed been expunged from the list 

 of radiated animals by some modern 

 writers, but in every point of their in- 

 ternal structure we shall find them 

 offer too many points of similarity to 

 permit of their expulsion from the class 

 under consideration, although they evi- 

 dently form the connecting link between 

 the Radiata and the lowest families of 

 the articulated division of the animal 

 kingdom. The genus Fistularia (Jig. 

 63) strikingly exhibits approximation to 

 the outward form of the ANNELIDA ; 

 and the anatomy of these creatures, 

 which we shall afterwards consider, 

 equally indicates the affinities which 

 unite them. 



(187.) We have already, when speak- 

 ing of the general division of the Echino- 

 dermata, put the reader in possession of 

 all that is satisfactorily known concern- 

 ing the structure of the Crinoid* ge- 



* K{/m, a lily'; tfiat, like. 



