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



Elpidia, Theel. 



Elpidia, Mem. sur l'Elpidia, nouv. genre d'Holothuries; Kongl. Sv. Vet. Akad. Handlingar, Bd. 24, No. 8, 1877. 



Body oval, or more or less oblong, about twice or thrice as long as broad ; sometimes 

 depressed posteriorly. Tentacles ten. The dorsal surfaces with processes commonly few 

 in number and mostly disposed only on its anterior part. Integument with calcareous 

 deposits composed of four more or less curved arms issuing from a common central 

 point, or from the ends of a more or less elongated central part, or from the sides of a 

 long slender spiculum, and provided with one to five processes directed outwards ; besides 

 these bodies there are often small wheels. 



Elpidia glacialis, The'el. 



Elpidia glacialis, Th6el, Note sur l'Elpidia ; Bihang till K. Svenska Vet. Akad. Handlingar, 



Band 4, No. 4, Stockholm, 1876. 

 ,, ,, Th^el, Memoire sur l'Elpidia ; Kongl. Svenska Vetenskaps-Akademiens 



Handlingar, Band 14, No. 8, Stockholm, 1877. 

 „ ,, Danielssen and Koren, Echinodermer fra den Norske Nordhavsexpeditionen; 



Nyt Mag. for Naturvidensk. xxiv. 3, Christiania, 1877. 

 ,, ,, Danielssen and Koren, Echinodermer fra den Norske Nordhavsexpeditionen, 



Nyt Mag. for Naturvidensk. xxv. 2, Christiania, 1879. 



Body oval, about thrice as long as broad. Mouth anterior, subventral. Anus posterior, 

 slightly dorsal. Tentacles of almost ecpaal size ; their terminal part bearing two larger 

 and some smaller retractile processes. Pedicels large, four along each side of the ventral 

 surface. The dorsal surface with rather long processes on each ambulacrum ; they vary 

 in number, and are more or less distinctly disposed in pairs. Integument transparent, 

 brittle, aud rough, with two sorts of calcareous deposits numerous : slender spicula of 

 different lengths, bearing near their middle and at some distance from each other two 

 pairs of arms, one on each side, and two short conical processes directed outwards ; and 

 very small, hat-shaped, scattered wheels. 



Colour glassy. Length, about 22 mm. Breadth, about 8 mm. 



Habitat.— Station 160. March 13, 1874. Lat, 42° 42' S., long. 134° 10' E. Depth, 

 2600 fathoms; bottom temperature, 0"2° C. ; red clay. Only one specimen was brought 

 home by the Challenger Expedition. Besides this, a great many individuals were taken 

 in the Sea of Kara at a depth of 50 to 150 fathoms by the Swedish Arctic Expeditions, 

 1875 and 1876, and likewise a not insignificant number in the North Atlantic ocean by 

 the Norwegian North Atlantic^Expedition. 



As has been mentioned, only one individual of this species was brought home by 

 the Challenger Expedition. The discovery of this specimen in a locality so far south as 

 the neighbourhood of the Antarctic sea is of the greatest interest, considering that 

 this species during the last six or seven years has been found living rather commonly in 



