580 



CLARK : RECENT CRINOIDS 



which they live; but there are one or two points upon which 

 further emphasis may well be placed by presentation in a some- 

 what different light. 



Fig. 1. The frequency of the families of recent crinoids at different tempera- 

 tures. 



The number of crinoid families occurring within the several 

 divisions of 2° F. (fig. 1) which collectively make up the entire 

 range of the class is as follows: 



80° and over 4 



78°-80° 6 



76-78 6 



74°-76° 9 



72°-74° 9 



70°-72° 14 



68°-70° 13 



66°-68° 13 



64°-66° 14 



62°-64° 16 



60°-62° 17 



58°-60° 16 



56°-58° 16 



54°-56° 15 



52-54° 15 



50°-52° 11 



48°-50° 11 



46°-48° 10 



44°-46° 10 



42°-44° 10 



40°-42° 11 



38°-40° 12 



36°-38° 9 



34°-36° 7 



32°-34° 6 



30°-32° 3 



28°-30° 2 



26°-28° 1 



