Fig. 460. A diagram of the 

 apical nervous system of 

 Antedon. From Sedgwick, 

 after Ludwig. a. axial cords 

 of the arms ; Bi, first 

 brachial ossicle; CD, centro- 

 dorsal; Ri, Rz, R2, radiah. 



B 



,'perist. 



Fig. 461. Pelmatozoa. A, Rhizocrinus, x about 2^. From Sars. B, Thecal 

 plates of a cystoid with diplopores. C, Plates with pore-rhombs. D, Edrio- 

 aster bigsbyi. After Bather, amb. ambulacra on which the covering plates 

 remain; An. anus; flp. flooring plates of ambulacra; ia. interambulacrum ; 

 ?}iad. madreporite ; /)m5L peristome ; /)or. pores (for tube feet?). 



