f'AU'AREA. 43 



usually slightly bent to the opposite side from the outer cud, giving tin 1 

 spicule an S shape. The outer cud is slightlv swollen and roughened. 

 The thickness varies very irregularly throughout the length, 550 /A to 

 950 p. long x 20 p. to 28 p. thick. Many of these spk-ules have long 

 flattened areas just below the outermost bend, looking as it the spicule 

 had been diverted by contact with a plane surface. 



There are minute spiued oxea of two type-; : 



(l>) Straight, refriugcut, and thin, 50 p. long x 1 '2 p. thick. 

 (c) Curved, hastate, and thicker, 55 p. long x 4 p. to 5 p. thick. 



The triradiates are of two sorts : 



(<1) Approximately regular triradiates from the dermal cortex and bodv-wall 

 with straight rays, tapering slightly to near their extremities, then sharply 

 pointed. The rays and angles are nearly but not exactly e<jual. Kays 

 110 /A to 220 p. long X 8 p, to 12 p, thick. 



('/) Large alatc triradiates from the body-wall. Basal rays straight, tapering 

 moderately, then fairly sharply pointed, 400 /A to 500 /x long x 1 2 /A to 

 14 p. thick. Paired rays nearly straight, tapering, then sharply pointed, 

 1C.O/A long X 1-2 p. to 14 p. thick. Oral angle 120 to 145. 



i / ) (.'li'nti-tiin-*. 1'iasal ravs straight, tapering slightly to near the end. then 

 sharply pointed, 300 p. to 500 /A long X lip. to 12 /A thick. Paired rays 

 straight, 120 p. to I GO p. long x 10 /A to 12 /A thick. Ural angle 115 to 

 150. Angle of fold very variable, 115 to 160. Apical ray nearly 

 straight, sharply pointed, 100 p. long x 8 /A thick. Set-off moderate. 

 Angle between apical ray and basal ray 165. 



Oscular spiciili'H. Near the oscule type (n) spicules get smaller, :\^,0 p. long x 

 20 p. thick. 



(//) Straight, strongly hastate, thin, spiued oxea forming the fringe, 100 p. to 

 200 p. long x 1 p. to 3 p. thick. The spear-head is swollen at the junction 

 and very sharply pointed. These spicules arc also found in the oscular 

 collar a short distance below the' edge lying tangeutially and occasionally 

 projecting. 



(//) Small ijuadriradiates from the oscular edge. Basal ray straight, pointed, 

 50 p. to 90 p. long X G p. thick. Paired rays equal and bent slightly down. 

 30 p. to GO p. long X 5 p. thick. Apical ray straight, pointed, 20 /x, long x 

 5 p. thick. Oral angle 1GO. 



(/) Large quadriradiates lining the oscular collar. Basal ray straight, tapering 

 uniformly to a fine point, sometimes bent backwards in side view. Length 

 near oscular edge 200 p., increasing considerably lower down. Thickness 

 7 p. to 9/i. Paired rays equal, straight or slightly bracket-shaped, 110 p. 



