242 ME. W. PERCY SLADEN ON THE 



longest ; they are slightly tapered at their extremity, and just 

 protrude beyond the margin, which is feebly festooned between. 



Colour, in alcohol, greyish white, nearly transparent. 



Station 146. Lat. 46° 46' S., long. 45° 31' E. Depth 1375 

 fms. ; bottom temperature 1°'5 C. ; Glohigerina-oozQ. 



Station 147. Lat. 46° 16' S., long. 48° 27' E. Depth 1600 

 fms. ; bottom temperature 0°'8 C. ; Glohigerina-oozQ. 



In a specimen from Station 147 four seems to be the normal 

 number of ambulacral spinelets, the adoral one being relatively 

 smaller, and the transverse tendency of the series upon the plate 

 being even more marked than in the specimen from which this 

 description is taken. In this specimen (from Station 147) an 

 additional pair of superficial secondary mouth-spines is present, 

 making three pairs, and the innermost pair of mouth-spines 

 proper are nearly as large as the adoral pair of secondaries. 



Benthastee, n. gen. 

 Form depressed, marginal contour stellato-pentagonoid, dorsal area 

 convex, aetinal area plane. Supradorsal canopy rudimentary. No mus- 

 cular fibrous bands. No spiracula. Nidamental cavity more or less aborted. 

 Paxillse with subfascicular crowns ; spinelets trilaminate, of extraordinary 

 length, delicacy, and number, protruding the greater portion of their length 

 naked beyond the supradorsal membrane. Paxillse probably devoid of 

 investing membrane. Papulae simple globular sessile sacs, comparatively 

 large. Special dorso-lateral plates at the extremity of the rays. Ossicles 

 of the dorsal surface cruciform, greatly attenuated ; the whole calcareous 

 framework being reduced to a minimum. Ambulacral spinelets one or two, 

 long, needle-shaped, independent, not united by membrane. Aperture- 

 papillae more or less modified. (?) Segmental apertures aborted. Mouth- 

 plates of the Hymenaster type. Two pairs of secondary mouth-spines, 

 robust, clavate, thorny, probably without saccular membrane. Mouth- 

 spines proper 2 or 3, the innermost resembling the anterior pair of 

 secondaries, only rather smaller, the others pointed. Actino-lateral spines 

 merged in the aetinal floor. 



The superficial aspect of this genus recalls, to a certain extent, 

 that of Korethraster , from which, however, it is structurally 

 widely separate. The rudimentary supradorsal membrane and 

 the long fasciculated naked paxillar spinelets, protruding far 

 beyond the membrane, readily characterize the genus from 

 Hymenaster ; whilst the simple, independent ambulacral spines, 

 not forming combs and not webbed, at once distinguish it from 

 Marsipaster, the only other form to which it can be compared. 



