MONOGRAPH OF TIIE EXISTING CRINOIDS. 

 C. 



73 



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

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

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

 plates such as interradials which may be found; by some authors tho disk is 



FIG. 35. AN ARM OF A SPECIMEN OF STYLOMETRA SPINIFERA FROM CUBA SHOWING THE DISTRIBUTION OF THE SYZYGIES; AT 

 THE RIGHT ARE INDIVIDUAL SYZYGIAL PAIRS ENLARGED TO SHOW THE PROGRESSIVE DIFFERENTIATION OF THE HYPOZYGAL AND 

 EPIZYOAL. 



included in the term calyx, though as a rule only when it is furnished with a 

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

 pp. 174-182). 



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

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



70140 Bull. 82 15 6 



