REPORT ON THE HOLOTHURIOIDEA. 15 



Parelpidia, n. gen. 



Body very elongated, cylindrical, Synapta-like, five or six times longer than broad. 

 Tentacles ten. The dorsal surface in its anterior part only provided with a few rudi- 

 mentary, almost inconspicuous processes. The ventral surface without pedicels in its 

 anterior part. Integument with calcareous deposits, composed of four arcuate arms 

 directed towards the inside of the body, and one central, long and straight process 

 directed outwards. 



Parelpidia elongata, Thdel (PI. I. figs. 3, 4). 



Elpidia elongata, Theel, Preliminary Report on the Holothuridre of H.M.S. Challenger, p. 17. 



Mouth anterior, subterminal. Anus posterior, dorsal. Tentacles of almost equal size ; 

 their terminal part rather large, with numerous small retractile processes, and with an 

 incision in the outer edge. Pedicels, eight along each side of the ventral surface, and 

 behind the anus an azygous one, flat and twice as broad as the others, having the point 

 obtuse and incised in its middle ; the two or three posterior pairs flat, broader and longer 

 than the others. The dorsal surface with about three pairs of very small, rudimentary 

 processes on its anterior part. 



Colour in alcohol, light grey. Length, about 150 mm. Breadth, about 25 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 incomplete 

 specimen. 



The body is of almost equal breadth throughout, the posterior end being suddenly 

 rounded. The mouth, the rather large oral disk, and the tentacles are slightly bent 

 towards the ventral surface. The anus is large, perfectly dorsal, and placed near the 

 posterior end of the body. The anterior part of the body is destitute of pedicels, the first 

 pair being situated almost at the middle of the body or somewhat anteriorly. The 

 pedicels, eight along each side, are disposed in pairs ; the odd pedicel is situated behind 

 the anus at the posterior end of the body. Three different kinds of pedicels are to be 

 distinguished. The first five or six pairs, 8 or 10 mm. long, are almost cylindrical, with 

 the end a little enlarged. The two or three posterior pairs are considerably longer, 

 almost 13 or 14 mm., flattened, broadest at the middle, and tapering towards the end. 

 The odd pedicel is also flat, and twice as broad as the others ; it is not longer than 

 about 7 mm., and its breadth is a little greater than its length. The free obtuse end of 

 this pedicel is distinctly emarginated, and its upper and lower surfaces are concave in the 

 middle. The processes of the dorsal surface are very small, visible only as spots on the 

 anterior part of the back ; they are six in number and irregularly disposed, three along 

 each ambulacrum. The perisoma is rather thick, with five longitudinal lines marking 



