.REPORT ON THE HOLOTHURIOIDEA. 55 



Scotoanassa, 1 n. gen. 



Body very depressed, almost flat, with an extension of the body-wall constituting a 

 broad rather flat brim round its anterior and posterior ends. Tentacles ten. The dorsal 

 surface with processes only on the margin of the anterior brim. The ventral surface with 

 pedicels only round the margin of the posterior brim. Integument with calcareous 

 deposits, composed of four arms and four outwardly directed processes. 



Scotoanassa diaphana, n. sp. (PI. IX. figs. 3-5). 



Body about thrice as long as broad. Mouth ventral, behind the anterior brim. Anus 

 dorsal, immediately in front of the posterior brim. Tentacles of almost equal size ; their 

 terminal part with two rather long, digitiform processes and with a number of small, 

 branched, retractile projections. Processes of the dorsal surface very small, four on the 

 margin of the anterior brim. Pedicels of the ventral surface ten, round the margin of 

 the posterior brim ; the two middle ones very small. Integument thin and transparent ; 

 calcareous deposits slightly scattered, composed of four spinose, slightly curved arms, 

 diverging two from each end of a long rod-like central part ; each arm with a spinose 

 process directed outwards. 



Colour in alcohol, white and glassy. Length, about 50 to 55 mm. Breadth, about 

 18 to 20 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. One specimen. 



The body is distinguished by its slight height, the dorsal and ventral surfaces 

 possessing about the same degree of convexity. Four elongated conical canals pass 

 through the brim round the anterior part of the body, each running out into a correspond- 

 ing almost imperceptible process on the margin of the brim. By closer examination it is 

 easy to discover that the two left hand canals communicate with the left dorsal ambulacrum 

 and the two others with the right. The brim has the appearance of being constituted 

 by four dorsal processes, which are intimately united with each other by an exten- 

 sion of the connective tissue layer of the body-wall, leaving only their tops free. The 

 brim, which thus belongs to the dorsal surface, reaches its greatest breadth, about 8 mm., 

 anteriorly, and decreases regularly towards each side. The posterior brim, which is 

 thin, flat, and almost equally broad, about 7 mm., belongs for a similar reason to the 

 ventral surface, its pedicels, which project around its margin, being in connection with 

 long canals which penetrate the brim and communicate with the ventral lateral 

 ambulacra. The two middle pedicels are quite unimportant and almost impercep- 

 tible. On account of this arrangement of the two brims the mouth has a more 

 distinct ventral position, and the anus is more perfectly dorsal than is usually the 

 case. The tentacles (PI. XLIV. fig. 9) are rather large, and end in two long digitiform 



' 2x»rof = darkness. 



