406 



ZOOLOGY 



SECT. 



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

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



syz cir 



FIG. 331. Aboral view of Antedon. c. centro-dorsal ossicle ; cir. cirrus ; Rl R,* ., the three 

 radial plates of one column ; syz. syzygy or aiticulation. (After MacBride.) 



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

 with which the bases of the cirri are connected. The cirri cir?' 



FIG. 332. Antedon, oral (upper) surface of the central disc. an. anus 

 (From Vogt and Jung.) 



mo. mouth. 



consist each of a row of slender ossicles, covered, like all the rest 

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



