NO. 10 PHYLOGENETIC STUDY OF RECENT CRINOIDS CLARK ^7 



III. Disk 



The condition of the orals, whether with or without upturned 

 edges. 



IV. Arms 



The structure of the arms, whether a linear series of ossicles with- 

 out IBr series, or dividing- one or more times, or with IBr series. 



BOURGUETICRINID^E 



I. Calyx 

 The individual occurrence, or fusion, of the basals. 



IV. Arms 

 The condition of the IBr 2 , whether axillary or not. 



API0CRINIM2 



II. Column 



The presence or absence of nodals. 

 The presence or absence of cirri. 



PHRYNOCRINIMS 



I. Calyx 

 The method of reduction of the calyx. 



THE CRINOID FAMILIES CONSIDERED AS THE SUM OF THE 

 CONTRASTED CHARACTERS EXHIBITED BY THEM 



If we take each crinoid family, and, for each of the structural 

 divisions given (Calyx, Column, Disk, Arms, Pinnules and General 

 Structure), add the primitive characters (i) and the specialized 

 characters (2), the difference between the two totals will give us 

 an index of the relative condition of specialization of each of the 

 different structural units. 



The figures are as follows : 



PENTACRINITID^E 



Calyx 8 (1) 9 (2) difference 1 (2) 



Column 1 (1) 5 (2) 4 (2) 



Disk 4(1) 5(2) " 1(2) 



Arms 9 (1) 9 ( 2 ) o 



Pinnules 5 (1) 5 (2) 



General 1(1) 1 (2) o 



28 (1) 34 (2) difference 6 (2) 



