CALOARBA. 41 



The oscular collar is thick and densely packed with spicules. On the inside are 

 quadriradiates lying tangentially with the basal rays downwards, and outside are 

 • triradiates. The rim, which has no fringe, is formed of tri- and quadriradiates, with 

 oral angles of nearly 180°. There is a diaphragm in one specimen. 



Spicules (Fig. 128). 



Oxea. — There are three sorts of Oxea : — 



(a) Large projecting oxea, straight for about two-thirds of their length, then 

 bending smoothly to one side. The inner (straight) end tapers gradually 

 to a point. The outer end is blunt, shaped like the end of a thumb. 

 Most of the oxea are about the same size, 460 ju, long x 24ju, thick. 

 Maximum size, 640 /a x 25 ju,. There are a few smaller, imperfectly formed, 

 possibly young, oxea. 



The minute spined oxea scattered throughout the body and forming the flagellated 

 chamber skeletons are of two forms : — 



(h) Straight, refringent, thin, slightly spined, 50 /li x 2 /x. 



(c) Curved, hastate, thicker and well spined, bO jx to 60ju,x 2'3/a to 3'1/a. 



The junction of the spear-head is marked by a ring of four or more large 



spines. 



The Triradiates are of one sort : — 



{d) Alate triradiates from the dermal cortex and body-wall. These vary very 

 much in size and proportions. Most have the paired rays only slightly 

 shorter than the basal ray, but occasionally there is great disparity. Basal 

 ray straight, tapering uniformly to a sharp point, 130 ju, to 330 /a long x 

 8 /A to 15)u, thick. Paired rays equal, nearly straight, but slightly 

 irregular, 90 /a to 320 /a long x 8 ^ to 14 /x thick. Oral angle 108° to 115°. 

 {e) Chiactines. — Basal ray straight, tapering uniformly to a sharp point, 460 /a 

 to 580 /A long X 14)u,to 18jli thick. Paired rays straight, bluntly pointed, 

 160 yu to 280 /a long X 14 ju, to 16 ju, thick. Oral angle 160°. Angle of fold 

 155° to 165°. Apical ray nearly straight, pointed, 100 /a long x 12/a 

 thick. Set-over small. Angle between apical ray and basal ray 175°. 



Megapogon crisp atus.* 



(Plate XXVIL, Fig. 2, and Plate XXXVIIL, Figs. 131-136.) 



There are four specimens of this new species in the collection, all found together. 



The sizes are 9 mm. x 3 mm. ; 6 mm. x 2 mm. ; 6 mm. X 3 mm. ; 4 mm. x 2 mm. 



They are vase-shaped, white or pale orange as preserved in spirits, with a curly surface 



* Grispatus, curly-haired. 



2 N 2 



