406 



ZOOLOGY 



SECT. 



The aboral side of the disc is occupied by a large, flat, pentagonal 

 ossicle, the centro-dmsal ossicle (Fig. 331, c; and Fig. 334, CD), 



Fiii. 331. — Aboral view of Antedon. c. centro-dorsa] ossicle ; cii\ eirrus ; R,'^ li,^ ii,^ the three 

 radial plates of one column ; sj/r. syzygy or articulation. (After MaeBride.) 



bearing on its outer surface a number of little cup-like depressions, 

 with which the bases of the cirri are connected. The cirri (cin') 



Fin. 332. — Antedon, oral (upper) surface of the central disc. an. anus ; mo. mouth. 

 (From ^'^>gt and Jung:.) 



consist each of a row of slender ossicles, co\'ored, like all the rest 

 of the animal, with epidermis, and connected together by means 



