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



one (Antedon denticulate), from 49 fathoms at Station 190 in the Arafura Sea, can be 

 called a littoral species. The remainder all belong to the continental or to the abyssal 

 zone. Most of them have covering plates and generally also side plates to the ambulacra ; 

 and the two ten-armed forms of Antedon from the Challenger dredgings which have 

 plated ambulacra but the rays not flattened laterally (Accela-growp) are even more 

 restricted in their distribution. One was found in 140 fathoms at Station 192 in the 

 Arafura Sea, and the other in 500 fathoms off the Meangis Islands (Station 214). 



Not only are the ten-armed species of Antedon the most widely distributed as a 

 group, but they also have the most extensive individual range. Antedon eschrichti and 

 Antedon quadrata of the Arctic Ocean were dredged by the Challenger in lat. 43° N. 

 Antedon phcdangium ranges from the north of Scotland to Morocco and throughout the 

 western basin of the Mediterranean. The Protean Antedon rosacea also occurs in 

 the Mediterranean, extends from the Fseroe Banks to the Canaries, possibly even to 

 Cape Verde and the equator, and is perhaps also found on the American coast; whde 

 Antedon carinata is distributed between the parallels of 15° N. and 35° S., through 

 the Indian Ocean from Java 1 to Zanzibar, along the Atlantic coast of South America from 

 St. Lucia to Eio Janeiro, and is also found at Valparaiso. 



None of the multibrachiate forms of Antedon have anything like this geographical 

 range. In the western North Atlantic there is no species with more than ten arms north 

 of Florida, and the dimorphic Antedon lusitanica is the only one known on the eastern side. 

 This last and those from Japan are the most northerly multibrachiate forms, while Antedon 

 setosa from off Tristan da Cunha and the various species inhabiting Port Jackson and 

 near the Kermadecs are the most southern representatives of these many -armed types of 

 Antedon, which have almost exactly the same range in latitude as the genus Actinometra. 

 Examples of each of the two great groups, those with two and those with three distichal 

 joints, occur in the Caribbean Sea, and they are abundant between the Society Islands 

 and the Red Sea. But, as we have just seen, they have a very limited bathymetrical 

 range, only appearing at seven Challenger stations between 100 and 630 fathoms, 

 and at none where the depth exceeded this latter limit. 



In some of the Antedon-syyecies dredged at all these seven stations the secondary arms 

 consist of three distichal joints, the axillary with a Syzygy, but at two of them bidistichate 

 forms also occurred, together with species of Actinometra ; and the single " Porcupine " 

 Antedon with more than ten arms is Antedon lusitanica from 740 fathoms, in the North 

 Atlantic, which sometimes has a distichal series of two joints. There are no tridistichate 

 species of Antedon in the North Atlantic, outside the Caribbean Sea ; though they occur 

 in the South Atlantic at Tristan da Cunha and Ascension, and at five stations below 

 100 fathoms in the Western Pacific and Australasia. 



On the other hand, the bidistichate series represented by Antedon lusita?iica does 



1 See the remarks on this subject on p. 202. 



