ECHINOIDEA AND OPHIUROIDEA 



By Th. Mortensen 



(Plates I-IX; text-figs. 1-53) 



INTRODUCTION 



THIS report deals with the Echinoids and Ophiurids collected by the 'Discovery', 

 the 'Discovery 11' and the 'William Scoresby' in the years 1925-35, mainly in 

 the sub-Antarctic and Antarctic seas, from the Magellanic region to South Georgia, the 

 Palmer Archipelago, the South Sandwich Islands, and off Marion Island. Some few 

 hauls made off Gough Island, Tristan da Cunha, Ascension, South Africa, Angola, 

 Annobon in the Gulf of Guinea, and in Cook Strait, New Zealand, have added a not 

 inconsiderable number of species. 



It has been thought preferable in the systematic account to deal with all this material 

 together — not to arrange it according to localities. 



Although our knowledge of the Echinoid and Ophiurid fauna of the sub-Antarctic 

 and Antarctic seas is rather extensive, particularly owing to Koehler's divers reports on 

 the collections made by the 'Belgica', the 'Scotia', the 'Pourquoi-Pas?', the Swedish 

 Antarctic Expedition and the Australasian Antarctic Expedition, quite a considerable 

 number of new forms are contained in the Discovery collections, a fact tending to 

 indicate that we are still far from having a complete record of all the species occurring 

 in the sub-Antarctic and Antarctic regions, not to mention the distribution and biology 

 of these forms. But this much we do know, that the sub-Antarctic-Antarctic Echino- 

 derm fauna is exceedingly rich, far exceeding that of the Arctic-sub-Arctic region. 



The Discovery collection has afforded me a much desired opportunity of clearing up 

 various little known forms, particularly the Ophiurids from South Georgia described 

 by Studer ; also some of those described by Koehler needed revision — not to speak of 

 those described by Jeffrey Bell — a revision which has led to a not inconsiderable reduc- 

 tion in the number of species hitherto recorded from these regions. I beg to express here 

 my great indebtedness to the authorities of the British Museum, London, to Professor 

 Dr W. Arndt of the Berlin Museum, and to Professor Dr Sixten Bock of the Stockholm 

 Museum, Dr E. Leloup of the Bruxelles Museum, and Dr A. Panning of the Hamburg 

 Museum, for lending me type material of various old, insufficiently known forms, thus 

 enabling me to give additional information about them and to supply new illustrations 

 of them, where it was thought desirable. 



The Echinoid collection does not contain any large number of species, thirty-one in 

 all (including two varieties), and only three of these, Notechinus marionis, Abatiis curvi- 

 dens and Amp/upneustes similis, are new to science. 



