MONOGRAPH OF THE EXISTING CRINOIDS. 



G. 



73 



Calyx. — The base of a crinoid; that is, the part remaining after the stem (or centro- 

 dorsal) and postradial structures have been removed; it includes the infra- 

 basals (when present), the basals and the radials, with any supplemcntaiy 

 p]ates such as mterradials which may be found; by some authors the disk is 



Fig 35 -an akm of a specimen of Stylometea spinifera from Ci;ba showing tue nisTRiDUTioN "/J"^ j;'-";"'^-";" 



THE RIGHT ARE INDIVIDUAL SVZVGL.L PAIRS ENLARGED TO SHOW THE PROGRESSIVE DIFFERENTIATION OF THE HTPOZ.GAL AND 

 EPIZYGAL. 



included in the term calyx, though as a rule only when it is furnished ^^•ith a 

 solid pavement of calcareous plates. (See figs. 2, p. 61, and 3, p. 62, and 



pp. 174-182). . . , , , 1 



The calyx is not a morphological unit, for it mcludes the true coronal 

 plates, and, in addition, the radials, which are true arm plates. 



79140°— Bull. 82—15 6 



