CALCAREA. 19 



Spicules (Figs. 55 and 56). 

 The Oxea are of one wort : — 



{(i) Very large bent projecting oxea, of all sizes from 400 /x to 1,830 m long, x 

 20 m to 33 m thick, pointed at both ends, usually straight for about two- 

 thirds of their length, then bent at two or three points angularly, the end 

 being often bent through a total angle of 125° from the axis of the 

 straighter portion of the spicule. The points where the angular bends 

 occur are often marked on the convex side by flattened areas, as if the 

 spicule had been deflected Ijy contact with a plane surface. 



The Triradiates are of one sort : — 



(A) Alatc triradiates of very variable shape. There is no distinction between 

 the gastral, body wall and dermal triradiates. Basal ray straight, tapering, 

 sharply pointed, 190 m to 360 m long x 10 m to 14 m thick. Paired rays 

 straight or bent slightly up or down, IGOm to 220 m long x 10 m to 14 m 

 thick. Tapering slightly and rather Ijluntly pointed. Oral angle 110° to 

 145°. 



Qaadrlrnd'tates. — There is one sort of (|uadiiradiate : — 



((') Alate quadriradiates from the gastral cortex, basal ray straight, tapering to 

 a sharp point, 280 m long x 12 m thick. Paired rays equal, slightly bent 

 upwards, 140 to 220 m long x 10 to 12 m thick. Oral angle about 130° 

 folded backwards, i.e. away from the face bearing the apical ray. Angle of 

 fold about 170°. Apical ray 40 m hmg x 8 to 10 m thic-k, sharply pointed, 

 bent orally. 



Osculnr spicnlc'ft. 



(/') The oscular fringe consists of short club-shaped oxea tapering to a point at 

 the inner end and lient near the outer end, whicli is rounded, 150m to 

 230m long X 12 m to 45 m thick. The thicker spicules are the commonest. 

 The triradiates at the edge have an oral angle of nearly 180°. 



Leucandra hiberna.* 

 (Plate XXXI., Figs. 57-58.) 



There are two specimens of this new species in the collection, one straight, vase- 

 shaped, 7 mm. X 1| mm., the other bent through at right angle, 6 mm. x 1 mm. In 

 colour they are dull yellow as preserved in spirits, and appear minutely hispid to the 

 naked eye. 



The structure of the body wall, which surrounds a large gastral cavity, is shown in 



* Most of the specimens were collootcd at the ' Discovery's ' Winter Quarters. 



