64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



THE CORRECTED RELATIVE SEQUENCE OF THE RECENT 

 CRINOIDS ON THE BASIS OF THE RELATIVE SPECIALIZA- 

 TION OF EACH OF ITS COMPONENT STRUCTURAL UNITS 



In order to appreciate correctly the phylogenetic sequence of the 

 recent crinoids on the -basis of the relative specialization of each of 

 its component structural units, it is necessary to apply as a correction 

 the foregoing' figures, representing the relative state of the specializa- 

 tion of each structural unit in terms of the least specialized. 



To do this we may make use of the table given on p. 63, modified 

 so that the least specialized structural unit will be indicated by the 

 number 1, and the most specialized by the number 6 (that is, with 

 the figures reversed), multiplying each number by the relative value 

 of the structural unit under consideration in terms of the pinnules. 



Applying both sets of figures given above, we get the following 

 tables : 



Applying the figures of the first table : 



Calyx Column Disk Arms Pinnules General Total 



Holopodidae 144 



Pentacrinitidse ... 120 75 68 42 3 24 



Bourgueticrinidse. 96 



Apiocrinidse 72 



Phrynocrinidse ... 48 

 Plicatocrinidse ... 24 



Applying the figures of the second table : 



Relative standing 



of the families, 



the Plicatocrini- 



dx. being taken 



Calyx Column Disk Arms Pinnules General Total as ioo 



Holopodidae 16254 8136 4284 12264 2 11088 52028 259 



Pentacrinitidse.. . 13545 10170 8568 6132 3 5544 43962 219 



Bourgueticrinidse 10836 4068 6426 10220 1 11088 42639 213 



Apiocrinidas 8127 6102 8176 2 11088 33495 167 



Phrynocrinidse... 5418 4068 6426 4088 2 11088 31090 155 



Plicatocrinidse... 2709 2034 2142 2044 1 11088 20018 100 



The figures upon which these tables are based are : 



Holopodidae 6 4 2 6 2 2 22 



Pentacrinitidse 5 5 4 3 3 1 2I 



Apiocrinidas 3 3 4 2 2 14 



Bourgueticrinidse 4 2 3 5 1 2 17 



Phrynocrinidse 2 2 3 2 2 2 13 



Plicatocrinidse 1 1 1 1 1 2 7 



. It will be seen that these corrected figures give the same sequence 

 of families as the table summarizing the characters in each family 

 (p. 60), except that the Holopodidae come before the Pentacrinitidse. 



