230 MR. W. PERCY SLADEN ON THE 



second, or outer, moutli- spine is very much smaller, and placed 

 away from the inner mouth-spine, somewhat isolately on the 

 margin of the plate, and is directed horizontally. 



Actino-lateral spines about 21 on each side (of fairly large ones 

 only 18), the 6th from the mouth being longest ; this and all the 

 spines preceding it join close up in the median interradial line 

 with the corresponding spine of the neighbouring ray, whilst the 

 succeeding spines diminish by regular steps. Spines tapering 

 and pointed. Membrane made up of very fine fibres ; margin 

 very slightly festooned between the tips of the spines. 



Colour, in alcohol, white ; ambulacral furrows and sucker-feet 

 yellowish brown. 



Station 335. Lat. 32° 24' S., long. 13° 5' W. Depth 1425 fms. ; 

 bottom temperature 2°'3 C. ; Gloligerina-oozQ. Also off coast of 

 Portugal ; label marked ' Station I.-VII.' 



Htmekaster latebrostjs, n. sp. 



Marginal contour substellate ; interradial angles sharply in- 

 dented, the lesser radius being in the proportion of 63'6 per 

 cent.; i2 = 22 millim., r = 14 millim. Arm-angle acute; rays 

 broad and. sub triangular, with their margins gracefully curved 

 outward. General form depressed ; dorsal surface over the radii 

 more or less bombous ; radial areas not specially defined. Dorsal 

 membrane continuous up to the margin ; lateral fringe narrow, 

 regular, and sharply indented. 



Supradorsal membrane fine and semitransparent. Paxillae- 

 gpinelets uniformly distributed over the entire area, but present- 

 ing no definite order of arrangement. Pasillte with few spinelets, 

 4 to 5 being the general number. Muscular fibres numerous and 

 closely, though rather coarsely and irregularly, reticulated (inter- 

 crossed). Interspaces filled in with a delicate semitransparent 

 membrane, punctured with spiracula, usually one to a mesh, and 

 consequently rather widely spaced. Oscular orifice compara- 

 tively small, the valves lying almost level with the surface of the 

 dorsal membrane. 



Ambulacral furrows moderately broad, and subpetaloid in out- 

 line, tapering gradually to the extremity along the outer third of 

 the ray, and slightly constricted towards the actinostome. Ambu- 

 lacral spines 3 in number, short, cylindrical, rapidly tapering to 

 a fine point, and covered with thin membrane. Each series is 

 placed high in the furrow, and very oblique to the median line of 



