VIII 



ECHINODEBMA TA —PEDICELLARIAi 



395 



pedicellarije are further attached by a strong elastic fibrous band to 

 this same plate. 



h. Stalked pedieellapisB (Fig. 342, H, K). — Each pedicellaria 

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



R B C 



Fig. 342. — PediceUariSB of Asteroids. A, B, 0, D, E, F, Pseudo- or commencing pedicellaria; of 

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

 carinifera (after Gu^not). H, Stalked straight pedicellaria diagrammatised (after Cu^not). J, 

 Basal port.ion of a stalked crossed pedicellaria of Asteracanthion ruhens (after Perrior). K, A 

 similar pedicellaria of AstEracanthion glacialis (after Cu^not). 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 ; 8, stem. 



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

 (didactyle) pedicellarise are either straight (forfleiform) 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 pedicellarise, straight, crossed, and 

 three-bladed. 



The crossed pedicellarife are found in very gi-eat 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 latter can be withdrawn (Fig. 344). 



