ICHTHYOCRINIDAE 



263 



The family ranges from the Silurian with three genera, through the Devon- 

 ian, culminating in the Lower Carboniferous with six genera, one of which 

 passes up to the Lower Coal Measures (Pennsylvanian), making it the latest 

 survivor of the Flexibilia. 



Geographically the family is equally well distributed ; two genera, Cleisto- 

 crinus and Synerocrinus are restricted to Europe; two, Metichthyocrinus and 

 Synaptocrinus, to America; while the other six occur in both hemispheres. 



Geological and Geographical Distribution 



Number of known species 



(Open figures indicate American, those marked ( ) European) 



Formation 



ICHTHYOCRINIDAE 



Ih 







American 



Approximate 

 European 

 Equivalents 



CO 



3 

 _C 



*d 

 CJ 

 O 



£ 



CO 



3 

 C 



'C 



CJ 



O 



CO 



"5 

 U 



CO 



3 



Ih 



IS 



u 





 ■a 







CO 



3 



a 





 O 



0. 

 cd 

 C 

 >. 



CO 



CO 



3 

 C 

 'C 

 



">. 

 



n! 

 O 



CO 



3 



a 

 "C 

 

 

 >> 



Ih 



3 



w 



to 



3 



.B 











"0 



CO 



3 



a 



IS 



3 

 £ 



CO 



u 



CO 



3 



c 

 'C* 











u 

 cu 

 C 

 >> 



00 



CO 



3 



'u 







IS 

 0, 



B 



< 



"3 

 

 H 





















1 





u 















1 





co 



3 

 O 



!_ 

 V 



'a 

 

 ja 

 u 



cU 



u 



u 

 a; 



O 



Kaskaskia 



Hurlet 

 Moscow 























18 





















(I) 



(I) 



Keokuk 









I 



















/Mountain 

 1 limestone 













3 



5 















I 



(3) 















(1) 



1 



c 

 .5 

 '5 

 

 > 



p 



Chemung 



Upper 

 Middle 

 Lower 























IO 



Hamilton 









I 



(2) 



2 



(I) 



1 











Helderbergian 



I 





2 



























c 



Niasjaran 



Wenlock 



3 



(5) 



1 



(I) 



I 

 (I) 

















12 



c/5 



Medinan 









































American species 



24 

 (16) 



5 

 (5) 



(I) 



4 

 (1) 



I 



3 

 (3) 



2 



(3) 



3 



5 



(I) 



I 



(I) 





European species 



Total species 





40 



10 



I 



5 



I 



6 



5 



3 



6 



I 



2 



40 





