234 ME. W. PEECT SLADEN ON THE 



Ambulacral furrows narrow, much constricted towards the 

 actinostome and at the extremity of the ray. Ambulacral spines 

 3, acicular, unequal in length, rather short, placed in line parallel 

 to the median line of the furrow, excepting towards the extre- 

 mity, where the series become rather oblique. The aboral spine 

 is almost aborted, and the middle one less than the adoral spine of 

 the trio ; this latter is invested with a widely expanded sacculus, 

 which makes the spine appear many times thicker than its com- 

 panion and nearly twice as long, the large sacculus usually taking 

 a pointed or sublanceolate form, whilst the small investment of 

 the aborted aboral spine is generally rounded and somewhat 

 knobbed. The aperture-papilla is remarkably large, elongately 

 oval, and with its membrane acumino-spatulate in shape, much 

 broader than the sacculated ambulacral spinelets, and often nearly 

 as long. 



Mouth-plates short and comparatively broad, with widely ex- 

 panded lateral flanges. No prominent keel at the line of junc- 

 tion, which is flatly rounded. Two robustly clothed, rather short, 

 obtuse secondary surface- spines on each plate, one near the 

 adoral edge, the other near the middle of the plate, both main- 

 taining a wide space between their corresponding spines on the 

 adjoining plate. About four mouth-spines proper on the hori- 

 zontal margin of each plate, moderately long, very wide at the 

 base, and sharply tapering ; the external one sometimes redu- 

 plified. 



Actino-lateral spines delicate, well spaced, the longest about 

 16th from the mouth ; none meet in the interradial line, but are 

 widely separate even at the angle ; the spines vary but little in 

 length up to this point, but diminish very raj)idly beyond. 



Colour, in alcohol, white. 



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

 fms. ; bottom temperature 1°"5 C. ; Gloligerina-oozQ. 



Htmenastee geometeicus, n. sp. 



Marginal contour substellate ; interradial angles well rounded, 

 the lesser radius being in the proportion of 52"3 per cent. ; S=42 

 millim.,r=22 millim., approximately. Eiadii greatly attenuated 

 and tapering, \sdth the fringe almost, if not quite, aborted towards 

 the extremities. Dorsal surface uniformly flat ; under surface 

 prominently convex. 



Supradorsal membrane thin and semitransparent, supported 



