A'HI 



ECHINODERMA TA PEDICELLARIA 



395 



pedicellariae are further attached by a strong elastic fibrous band to 

 this same plate. 



b. Stalked pedicellarise (Fig. 342, H, K). Each pedicellaria 

 rises from a short, soft stalk ; the blades, of which there may be two 



FIG. 342. Pedicellariae of Asteroids. A, B, C, D, E, F, Pseudo- or commencing pedicellariae of 

 various species. G, Sessile pedicellaria from the edge of the ambulacral furrow of Gymnasteria 

 <:ni'(i(ifera (after Cuenot). H, Stalked straight pedicellaria diagrammatised (a^ter Cuenot). J, 

 Basal portion of a stalked crossed pedicellaria of Asteracanthion rubens (after Perrier). K, A 

 similar pedicellaria of Asteracanthion glacialis (after Cuenot). 1, Calcareous blade of the forceps ; 

 2, basal piece ; 3, occlusor muscle ; 3i, axial muscles of the blades ; 4, opening muscle ; 5, axial 

 band ; 6, epithelium ; 7, body wall ; S, stem. 



or three, articulate with a basal skeletal piece. The double-bladed 

 (didaetyle) pedicellariae are either straight (forfieiform) or crossed 

 (foreipiform). Both kinds may be found in one and the same 

 animal. 



We select for description Asterias (glacialis), one of the Asteroids 

 most richly provided with pedicellariae, whose arrangement is specially 

 interesting. 



A. glacialis has three kinds of pedicellariae, straight, crossed, and 

 three-bladed. 



The crossed pedicellarise are found in very great numbers, thickly crowded 

 together on a soft cushion, which surrounds the base of the spines, and into which the 

 latter can be withdrawn (Fig; 344). 



