REPORT ON THE CRINOIEEA. 



130 



much wider geographical range than Metacrinus, also extends to a great -r depth ; while 

 the same contrast, including also thermal range, may be noticed between Antedon and 

 the stalked Crinoids generally. It is somewhat singular that this widely distributed 

 genus, which was dredged at 2900 fathoms in the Pacific and at 2600 fathoms in the 

 Southern Sea, should not have been met with between the latter dojith and IGOO 

 fathoms. 



O. The Association of the Genera at Particular Stations. 



The mode of grouping of the various genera of Crinoids, both stalked and free, whicli 

 have been obtained at different Stations and by the exploring expeditions of varii)u,s 

 countries, presents some points of interest. The Challenger dredged Comatulse at fortylive 

 Stations, and stalked Crinoids at sixteen. If the different North Atlantic expeditions of 

 the British and Norwegian Governments 1ie also reckoned, this last number rises to 28. 



A single species of stalked Crinoid w;is found at several Stations, unaccompanied by 

 any Comatulae, as shown in the following Taljle. 



Table IV. — Showing the numher of times that Isolated Species cf Stalked Crinoids 



have been Dredged. 



At eleven Stations during the Challenger and "Porcupine" Expeditions which yielded 

 stalked Crinoids, there were either more than one species, or if only one was obtained it 

 was associated with one or more species of Comatulae (see Table V.). Pentacriniis has 

 been found associated with all the Comatulid genera except Thaumatocrinus, which was 

 only obtained once in the Southern Sea, considerably beyond the most southern limit 

 of Pentacrinus. 



The " Blake," however, dredged Pentacrinus in shallower water than was worked by the 

 Challenger ; and found it associated with Actinometra at nine out of the fifty-four Stations 

 at which stalked Criiioids were obtained (see Table VI.). As in the case of the Challenger 

 and " Porcupine," the two species of Rhizocrinus were never found at the same Station. 



