68 



A. R. Clark — Groups of Recent Crinoids. 



Maximum 

 Range 



Thysanometrinae 549 



Zenometrinae 1588 



Perometrinse 209 



Heliometrinae . , 1600 



Bathymetrinae. 2820 



Pentametrocrinidae .. 1679 



Atelecrinidae 616 



Pentacrinitida 1 345 



Apiocrinid^e 375 



Phrynocrinid^e 44 + 



bourgueticrinidae.. 2628 



*HoLOPODIDJE 115 



Inadunata 2309 



Plicatocrinidjs 2309 



Average 

 Eange 



Mean 



depth of 



habitat 



Average 

 depth of 

 habitat 



338 



298 



216 



383 



809 



315 



133 



138 



114 



633 



800 



383 



1801 



1490 



1349 



1193 



951 



828 



308 



599 



753 



629 



678 



427 







753 



753 







620 



620 



1415 



1376 



1134 



115 



62 



62 



952 



1420 



1378 



952 



1420 



1378 



The range in depth covered by the families of crinoids 

 inhabiting the recent seas varies from 35 fathoms in the Ste- 

 phanometridse to a maximum of 2820 fathoms in the Bathy- 

 metrinae. The sequence of the families according to the 

 bathymetric range is as follows : 



Stephanometridae 



Phrynocrinidae 



Himerometridae 



Mariametridae 



Holopodidae 



Ptilometrinae 



Comasterinae 



Colobometridae 



Zygometridae 



Perometrinae 



Antedoninae 



Tropiometridae 



Comactiniinae 



35 fathoms 



44 + 



61 



84 

 115 

 134 

 140 

 140 

 153 

 209 

 250 

 278 

 288 



Calometridae 



Apiocrinidae 



Thysanometrinae 



Atelecrinidae 



Capillasterinae 



Charitoraetridae 



ZenometrinaB 



Thalassometrinae 



Heliometrinae 



Pentametrocrinidae 1679 



Plicatocrinidae 2309 



Bourgueticrinidae 2628 



Bathymetrinae 2820 



333 f 



ath( 



375 



u 



549 



u 



616 



it 



830 



C( 



1170 



ti 



1588 



tl 



1600 



u 



1600 



« 



Average range in depth for all families 732 fathoms 

 The several contrasting groups give the following figures : 



More specialized 



2900 fathoms 



Articulata 



Pentacrinitidae 2900 



Comatulida 2900 



Oligophreata 1600 



Less specialized 



Inadunata 2309 fathoms 



Bourgueticrinidae 2628 " 

 Pentacrinitida 1345 " 



Macrophreata 2900 " 



