i8 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



65 



The rejection of the column in the young- and the subsequent 

 adoption of a so-called free existence, is an example of specialization 

 through the suppression of an originally fundamental structure. 



Frequency at different depths Frequency at different temperatures 



r- ' 1 , ' v 



Degrees 

 Fathoms 1 2 Fahrenheit 1 "2 



O-IOO 2 I 80-75 O I 



IOO-200 2 I 75-70 2 I 



2OO-30O 2 I 70-65 I I 



3OO-4OO 2 I 65-OO I I 



4OO-5OO 2 I 60-55 I I 



5OO-60O 4 I 55-50 I I 



600-700 4 I 50-45 I I 



7OO-80O 4 I 45-40 2 I 



800-900 3 i 40-35 4 I 



900-1000 3 I 35-30 2 I 



IOOO-I5OO 2 I 30-25 I I 



I500-2000 2 I 



2000-3000 2 I 



1 3 



Average depth 785 fathoms 808 fathoms 



Average temperature 47-5° Fahr. 52.5° Fahr. 



1. Column jointed. „ .. • . T . . 



J Bathymetric Thermal 



range range 



Apiocrinidse 565-940 36.7-38.1 



Phrynocrinidae 508-703 38.1-40.0 



Bourgueticrinidx 62-2690 29.1-70.75 



Plicatocrinidse 266-2575 31. 1-43.9 



2. Column un jointed. „ .. T , . 



•" Bathymetric 1 hernial 



range range 



Holopodidee 5-120 71.0 



Not only are the Articulata and the Inadunata fundamentally pro- 

 vided with a column, but that column is primarily composed of 

 numerous short ossicles united end to end in the form of a long 

 jointed stem. 



The reduction of this jointed column to a simple calcareous base 

 is therefore a form of specialization over the original condition, as 

 is evident from a study of the earlier types, and from a study of the 

 developing young. 



The reduction of the primitive long jointed column to a single 

 spreading base is evidently an example of specialization through 

 suppression of the normal stem forming power. 



