24 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 65 



1. Cirri absent. Bathymetric Thermal 



range range 



Apiocrinidce (Carpenterocrinns).. .565 38.1 



Phrynocrinidse 508-703 38.1-40.0 



Bourgueticrinidae 62-2690 29.1-70.75 



Holopodidae 5-120 71.0 



Plicatocrinidse 266-2575 31. 1-43.9 



2. Cirri present. Bathymetric Thermal 



range range 



Pentacrinitidse 0-2900 28.7-80.0 



Apiocrinidse (Proisocrinus) 940 36.7 



The cirri, in contrast to the radicular cirri, properly speaking 

 are structures primarily associated with the calyx and not with the 

 column, though always arising from the latter. They are always 

 associated with the existence of a proximale, or modified proximal 

 columnal, upon which they are situated, and hence are almost entirely 

 confined to the Articulata. 



The presence of cirri is always correlated with a great reduction 

 in the size and number of constituent elements of the column, and 

 in the relative size and number of skeletal elements of the calyx. 



While undoubtedly a new structure, the cirri by their presence 

 always indicate a very high degree of reduction in the skeleton of 

 the calyx and of the column, and hence are always an index of 

 specialization through suppression of skeletal development. 



Frequency at different depths Frequency at different temperatures 



Degrees 

 Fathoms 1 2 Fahrenheit 1 2 



O-IOO 2 I 80-75 I 



IO0-200 2 I 75-70 2 I 



200-300 2 I 70-65 I I 



3OO-4OO 2 I 65-60 I I 



400-500 2 I 60-55 I I 



500-600 4 I 55-50 I I 



600-700 3 I- 50-45 I I 



700-800 3 I 45-40 2 I 



80O-9OO 2 I 4O-35 ' 4 2 



9OO-IOOO 2 2 35-30 2 I 



IO00-I5OO 2 I 30-25 I I 



1500-2000 2 I 



2OOO-3OOO 2 I 



1 2 



Average depth 783 fathoms 818 fathoms 



Average temperature '. . . . 47.5° Fahr. 51-3° Fahr. 





