CALTAREA. 43 



usually slightly Ix-nt to the opposite side from the outer end, giving the 

 spieule an 8 Hhapo. The uutor end in slightly swollen uud roughened. 

 The thickness varies very irregularly throughout the length, 550 ft to 

 950 /t long X 20 ft to 28 ft thick. Many of those spicules have long 

 Hattened areas just below the outermost licnd, looking as if the spicule 

 had been diverted by contact with a. plane surface. 



There are minute spiued oxea of two types : 



(b) Straight, refringent, and thin, 50ft long x 1 '2 ft thick. 



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



The triradinte* are of two sorts : 



(il) Approximately regular tri radiates from the dermal cortex and body-wall 

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

 pointed. The rays and angles are nearly but not exactly equal. Kays 

 UO/i to 220 ft long x 8/i to 12 ft thick. 



() Large alate triradiates from the Ixxiy-wall. Basal rays .straight, tapering 

 moderately, then fairly sharply pointed, 400 p. to 500 /x long X 12ft to 

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

 160 /x long x 12 ft to 14 p. thick. Oral angle 120 to 145. 



(/) Chiactines. Basal rays straight, tapering slightly to near the end, then 

 sharply pointed, 300 p. to 500 p. long x 1 1 ft to 1 2 p. thick. Paired rays 

 straight, 120 p. to IGO/x long x 10 ft to 12 ft thick. Oral angle 115 to 

 150. Angle of fold very variable, 115 t 100. Apical ray nearly 

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

 Angle between apical my and Iwisal ray 165. 



Oscular spicules. Near the osculc type (</) spicules get smaller, 330 p. long x 

 20 ft thick. 



(y) Straight, strongly hastate, thin, spined oxea forming the fringe, 100 ft to 

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

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

 collar a short distance below the edge lying tangentially and occasionally 

 projecting. 



(h) Small quadriradiates from the oscular edge. Basal ray straight, pointed, 

 50 ft to 90 ft long x 6ft thick. Paired rays equal and lent slightly down, 

 30ft to GO ft long x 5ft thick. Apical ray straight, pointed, 20 ft long x 

 5ft thick. Oral angle 160. 



(i) 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 ft, increasing considerably lower down. Thickness 

 7 p to 9 fu Paired rays equal, straight or slightly bracket-shaped, 110 ft 



