REPORT ON THE HOLOTHURIOIDEA. 19 



the North Atlantic Ocean and in the Arctic Ocean (Sea of Kara). El/pidia glacialis 

 seems able to exist under very various conditions ; the individual brought home by 

 the Challenger Expedition proves that it lives at the greatest depth, up to 2G00 fathoms, 

 while those from the Arctic sea are found at depths of only 50 to 150 fathoms. The 

 southern form differs in various points from the northern one, but the difference is of 

 very little importance. The dorsal surface bears only three pairs of processes, the first 

 on the anterior part, the second in the middle and the third on the posterior part of the 

 body. The number and position of these dorsal processes seem to be highly variable. 

 Some of the tentacles do not cpiite agree with the figure given by me in the above cited 

 memoir on El/pidia glacialis, but that dissimilarity is accounted for by the fact that only 

 the two larger processes were extended in the first individuals I saw, the other ones 

 being retracted. The small hat- or wheel-shaped deposits scattered in the integument 

 of the northern form have not been detected, but, from the fact that the comparatively 

 very large spicula are rather deformed, I suppose that these very minute deposits have 

 already been dissolved. It seems that the size of the animal considerably surpasses 

 that stated above, and this is especially the case with the individuals brought home 

 by the Norwegian North Atlantic Expeditions. El/pidia glacialis is easily dis- 

 tinguished from all other known forms of the same family by the peculiar shape of its 

 calcareous deposits, and from the other species of the genus Elpidia, by its singular 

 calcareous ring, of which I have given a detailed account in my above-mentioned 

 memoir. As to the ambulacral system and the wrong opinion expressed by myself 

 and Drs Danielssen and Koren, I refer to the anatomical part of this report. 



Elpidia verrucosa, Theel (PI. III. figs. 1, 2). 



Elpidia verrucosa, Thdel, Prelim. Report on the Holothuridse, p. 15. 



Body sub-ovate, nearly twice as long as broad. Mouth anterior, terminal. Anus 

 posterior, slightly dorsal. Tentacles of apparently equal size, their terminal part bearing- 

 small retractile processes. Pedicels rather large, nine along each side of the ventral 

 surface. The anterior part of the ventral surface destitute of pedicels. The dorsal sur- 

 face with two pairs of processes in its anterior part. Integument extremely brittle and 

 hard, with numerous, rather large, pyramidal papilla?, crowded especially on the back, 

 each papilla containing a calcareous deposit, composed of four long, spinose, arcuate 

 arms, directed towards the inside of the body, and one or two central large and straight 

 processes, directed outwards from the body. 



Colour in alcohol, light violet with some darker spots. Length, about 52 mm. 

 Breadth, about 28 mm. 



Habitat,— Station 299. December 14, 1875. Lat. 33° 31' S., long. 74° 43' W. 

 Depth, 2160 fathoms ; bottom temperature, 1'1° C. ; grey mud. One specimen. 



This species, of which only a single individual is preserved in the collection, has the 



