136 THE VOYAGE OF H.M.S. CHALLENGER. 



substantial limestone band which supports the covering plates but is not properly 

 segmented, into side plates. The ambulacra! skeleton does not extend to the end of the 

 pinnules, several joints of which are entirely without it, as in Antedon longicirra from the 

 same station, and in many Pentacrinida?. 



3. The Eschrichti- gYouj). 



This group is very well defined both in its zoological characters and in its 

 geographical and thermal distribution. Of the seven species which it at present contains, 

 three are Arctic and the remaining four Antarctic. Antedon eschrichti and Antedon 

 quadrata are widely distributed through the Arctic Ocean, reaching a latitude of 79° N, 

 and 81° N. respectively in Smith's Sound. They extend across the North Atlantic into 

 the Barents Sea, and Antedon eschrichti, at any rate, was dredged by Nordenskjold in the 

 " Vega " as far east as long. 92° 20' E.. In the East Atlantic both species are found as far 

 south as the parallel of 60° in the cold area of the Fseroe Channel ; but the Challenger 

 dredged them both off Halifax in lat. 43° 2' N. This is their furthest southern limit, and 

 the third Arctic species belonging to this group [Antedon barentsi) has as yet only been 

 found near Vardo in the Barents Sea. 



Two of the four Antarctic species occur in the Straits of Magellan, while the other 

 two were obtained by the Challenger at Stations 150 and 151, between Kerguelen and 

 Heard Island. The only species found at depths exceeding 200 fathoms are Antedon 

 eschrichti and Antedon quadrata, both of which extend downwards from the littoral 

 fauna, the former descending to 632 and the latter to 466 fathoms. The temperature 

 limits of this group are very well defined. There is no record of any of them having 

 been found in water of a higher temperature than 36° F. Antedon quadrata was 

 obtained at 29° and Antedon eschrichti at 30° in the cold area of the Fseroe Channel ; 

 while Antedon australis was dredged from a temperature of 35 c, 2 at Station 150. I 

 do not imagine that this is likely to have been greatly exceeded at any of the shallow 

 water localities, either in the Arctic or in the Antarctic Seas, where species of this group 

 have been obtained. They are not, however, the only Comatulse which occur in the colder 

 seas of the globe. Antedon prolixa was obtained in 25 fathoms at Discovery Bay 

 (lat. 81° 41' N.) together with Antedon quadrata, and has since been dredged in 

 abundance near Spitzbergen by the Norwegian North-Atlantic Expedition, from a depth 

 of 743 fathoms ; while the " Varna " found it at 50 fathoms in the Kara Sea. 



The " Porcupine " and " Triton " met with' Antedon hystrix in the cold area of the Fseroe 

 Channel where Antedon eschrichti and Antedon quadrata also occur ; while Antedon 

 tenella, which reaches a latitude of 79° near Franz Joseph Land, is common in the Barents 

 Sea and on both sides of the Atlantic down to 740 fathoms, with a thermal range of 

 from 30° to 50° F. 



