62 A. H. Clark — Study of Recent Crinoids. 



has developed along somewhat different lines from the other. 

 It is evident, therefore, that an ecological comparison between 

 recent and fossil forms is unsatisfactory unless based upon 

 strictly congeneric species. 



In the recent seas the stalked crinoids have been very largely 

 supplanted by a curious unstalked type, the comatulid, which 

 is most extraordinarily developed, though systematically it 

 forms only one (Comatulida) of the three sections (Comatulida, 

 Thiolliericrinida and Pentacrinitida) of the family Pentacrini- 

 tidse. Of the comatulids, represented in the recent seas by 100 

 genera included in 21 families, only 2 genera, both belonging 

 to the same family, are both fossil and recent. 



Considering all the recent crinoids together, we find that of 

 the 121 genera and 27 families occurring in the present seas, 

 7 genera representing 5 families and including 20 recent 

 species are known also as fossils. In addition to these there is 

 the genus Democrinus, including 1 species, the status of which 

 was explained above. 



In the following table are given all of the recent crinoid 

 genera which include fossil species, with the data for each. 



The recent species of Eudiocrinus are : 



Eudiocrinus indivisus (Semper) Eudiocrinus pinnatus A. H. Clark 



Eudiocrinus junceus A. H. Clark Eudiocrinus serripinna A. H. Clark 



Eudiocrinus minor A. H. Clark Eudiocrinus variegatus A . H. Clark 



Eudiocrinus ornatus A. H. Clark Eudiocrinus venustulus A. H. Clark 



The recent species of Catoptometra are : 



Catoptometra hartlaubi (A. H. Clark) Catoptometra ophiura A. H. Clark 

 Catoptometra magnified A. H. Clark Catoptometra rubroflava (A. H. Clark) 



The recent species of Isocrinus are : 



Isocrinus asterius (Lirme) Isocrinxis blakei (P. H. Carpenter) 



Isocrinus decorus (Wyville Thomson) 



The recent species referable to Millericrinus are: 



Carpenterocrinus mollis (P. H. Carpenter) 



Proisocrinus ruberrimus A. H. Clark 



The recent species of Democrinus are : 



Democrinus parfaiti Perrier Democrinus sabce (A. H. Clark) 



Democrinus rawsonii Pourtales Democrinus weberi (Doderlein) 



The recent species of Rhizocrinus are : 



Rhizocrinus lofotensis M. Sars Rhizocrinus verrilli A. H. Clark 



