MONOGRAPH OF THE EXISTING CEINOIDS. 



77 



Compound interpolated arm division. Arm division in which all the division scries 

 are 2, these two ossicles representing externally a true division series, but 

 internally the first two ossicles of a free undivided arm, as in Comatella and 

 NeocomateUa (see fig. 78, p. 131). 



Fio. 41. 



FIG. 42. 



Fio. 43. 



FIO. 44. 



FIGS. 41-14. 41, LATERAL VIEW OF THE CENTBODORSAL AND ARM BASES o? A SPECIMEN OF I'ONTIOMETRA INSPERATUS FROM THE 

 PHILIPPINE ISLANDS, ILLUSTRATING A SPECIES WITH WELL-SEPARATED RAYS AND DIVISION SERIES. 4-', VENTRAL VIEW OF 

 THE CALYX AND ARM BASES OF A SPECIMEN OF I'ONTIUMETRA INSPERATUS FROM THE PHILIPPINE ISLANDS, ILLUSTRATING A 

 SPECIES WITH WELL-SEPARATED RAYS AND DIVISION SERIES. 43, LATERAL VIEW OF THE CF.NTRODORSAL AND ARM BASES oF 

 A YOUNG SPECIMEN OF ASTEROMETRA MIRIFICA FROM THE Kl ISLANDS, ENTIRE (a), AND WITH ONE POSTRADIAI. SF.RIES 

 REMOVED (6), ILLUSTRATING A SPECIES WITH CLOSELY APPRESSED OR "WALL-SIDED" RAYS AXM DIVISION SKRIES. 44, VENTRAL 

 VIEW OF THE ARM BASES OF A YOUNG SPECIMEN OF ASTEBOMETRA MIBIFICA FROM THE Kl ISLANDS, ILLUSTRATING A SPECIES 

 WITH CLOSELY APPRESSED OR "WALL-SIDED" ARM BASES. 



Coronal plates. The plates which primarily form a ring about the apical area; 

 these are 10 in number and in the crinoids are arranged in 2 circlets, the 

 first, abutting upon or concealed by the column, consisting of 5 small plates 

 (infrabasals) which arc radial in position, the second, immediately beyond 

 the first, consisting of 5 larger plates (basals) which alternate with those of 

 the first and are therefore internulial in position. 



