TH E 



VOYAGE OF H.M.S. CHALLENGER. 



ZOOLOGY. 



REPORT on the Holotiiltjoidea dredged by H.M.S. Challenger during 

 the years 1873-1876. By H.talmar Theel. Part I. 



INTRODUCTION. 



When, at the request of Sir Wyville Thomson, F.R.S., I undertook to work out the 

 Holothurioidea dredged during the Challenger Expedition, I had not the least idea 

 of the value and richness of the material confided to my care. But the first 

 inspection made it evident that the forms from great depths, now displayed for the 

 first time, were of the greatest interest by making it manifest that Holothurians are 

 living there not merely in great numbers but belonging to many species, and that a 

 large majority of them present certain peculiarities that render them strikingly different 

 from the littoral forms hitherto known, and make them constitute perhaps the most 

 characteristic group of the whole abyssal fauna. As will be seen further on, I have 

 considered myself justified in placing them under a new order — Ektsipoda, 1 equivalent 

 to the Pedata and Apoda already known. Of that order I shall here give the syste- 

 matic and anatomical description. 



During the Swedish expedition to the Yenisei, in the year 1875, several specimens oi 

 a singular animal were found in the Kara Sea, on the north-east coast of Novaya Zemlya. 

 On a closer examination it was found to be a Holothurid, which I have described 2 

 under the name of Elpidia, the single representative of a new family, the Elpidiidse. 



1 This seems a more correct name than " Elasmopoda " used in the Preliminary Report 



J Memoire sur PElpidia, nouveau genre d'Holothuries. Avec cinq Planches. Presents a I'Academie Royalc di 

 Sciences le 8 Mars 1876. Kongl. Svenska Vetenskaps-Akademiens Handlingar, Bandet 14, No. 8, Stockholm, 1^77 



r\ (ZOOL. CHALL. EXP. — PART XIII. — 1881.) N 1 



