REPORT ON THE HOLOTHURIOIDEA. 97 



298. November 17, 1875. Lat. 34° 7' S., long. 73° 56' W. Depth, 2225 fathoms ; 

 bottom temperature, 1 "3° C. ; grey mud. One specimen. 



The body is 140 to 145 mm. long and reaches its greatest breadth, about 55 mm., 

 anteriorly at the mouth or immediately behind it ; it tapers slightly backwards. The 

 height of the body decreases gradually forwards so that its anterior, nearly semi-circular 

 end becomes rather thin and discoidal, and presents the aspect of a distinct head-part. 

 The ventral surface is completely flat, while the dorsal, on the contrary, is convex. 

 Another slightly smaller individual obtained at the same station (157) has its body very 

 much swollen and almost ovate on account of the great quantity of Diatomacese, &c, 

 which fills up the alimentary canal. The mouth is placed almost 25 mm. from the 

 anterior extremity of the body, being thus situated in the centre of the anterior, fiat, 

 discoidal part of the under surface. The large anus is ventral, and is placed 

 10 mm. in front of the posterior extremity of the body. The odd ambulacrum is in 

 connection with a number of small, round, retractile pedicels which are close set and 

 disposed in an indistinctly alternating double row. The pedicels on the edge of the brim, 

 which surrounds the body, are numerous and minute ; excepting the anterior ones, which 

 communicate with the dorsal ambulacra, all these pedicels belong to the ventral lateral 

 ambulacra. The back is furnished with five pairs of very minute processes, of which 

 the first is almost inconspicuous, aud situated 45 mm. behind the anterior extremity 

 of the body, while the last slightly larger pair is 75 mm. to 80 mm. distant from 

 that extremity. The enormous dorsal appendage which arises 10 to 15 mm. from the 

 posterior extremity of the body attains a length of 110 to 120 mm., and is almost of an 

 equal breadth throughout, 30 to 35 mm., or slightly tapering towards the free end; it is 

 flat, about 10 mm. thick, and forms a more or less distinct edge along each side. The 

 rounded terminal part of the appendage is provided with two processes, of which the one 

 is extended and digitiform, and measures 5 to 6 mm. in length. Those processes com- 

 municate with two wide canals, which penetrate the appendage in its length and open 

 into the dorsal ambulacra (PL XXXVII. fig. 10). The eighteen tentacles are almost of 

 equal size, or the ventral ones slightly smaller ; their large discoidal convex end carries 

 round the edge about sixteen small, simple, retractile processes. 



The perisoma is rather thick, and contains deposits in the form of four-armed cruci- 

 form bodies of various dimensions. The deposits in the outer layer of the dorsal integu- 

 ment (PI. XXXV. fig. 13) are closely crowded, with their arms rather arcuated, and 

 suppbed with a number of strong, short spines directed outwards ; the largest deposits 

 have their arms - 4 mm. to 0"24 mm. long, while those of the smallest reach only 

 0-06 mm. in length. The calcareous bocbes of the inner layer of the dorsal integument 

 (PL XXXV. fig. 14) are remarkable for having their arms very slender, almost straight, 

 and givino' off very long and narrow spines in all directions. The deposits of the ventral 

 surface (PL XXXV. fig. 16) do not lie so close set, and are commonly smaller and of a 



(ZOOL. CHAIX. EXP. PART XIII. 1881.) N 13 



