CALCAREA. 41 



The oscular collar is thick and densely packed witli spicnles. On th(> inside arc 

 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 ahout two-thirds of their length, then 

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

 to a point. The outer end is Itlunt, shaped like the end of a tliunib. 

 Most of the oxea are about the same size, 460 yu, long X 24 /x thick. 

 Maximum size, G40 /j. x 25 /x. There are a few smaller, imperfectly formed, 

 possibly young, oxea. 



The minute spined oxea scattered throughout the liody and forming the tlagellated 

 chamber skeletons are of two forms : — 



(A) Straight, rcfj'ingent, tliin, slightly spined, ,'")0|U, X 2 /x. 



(c) Curved, liastate, thicker and well spined, SO/x to CiO /u. X 2 • .'l /x to ;> • 1 /x. 



The junction of the spear-head is maikcd by a ring oi' four or more large 



spines. 



The Triradiates ai-e of one sort : — 



{(I) Alate triradiati>s tVom the dermal cortex and body-wall. These vary very 

 much in size and proportions. IMost have the paired rays only sHghtl)' 

 shorter than the basal ray, l)ut occasionally there is great disparity. Basal 

 ray straight, tapering unif(U'mly to a shar]) point, 130 /ix to 330 /x long x 

 8 /x to lo/u, thick. Paired rays ecjual, nearly straight, but slightly 

 irregular, 90 /x to 320 /x longx 8 /x to 14 /x thick. Oral angle 108° to 11,')°. 



{(') Chiactines. — Basal ray straight, tapering uniformly to a sharji point, 4(!0/x 

 to 580 /x long X 14/x to 18/x thick. Paired rays straight, bluntly pointed, 

 IGO/x to 280 jix long x U/x to 1 fi ja thick. Oral angle TOO''. Angle of fold 

 155° to ir)5°. Apical ray nearly straight, pointed, 100/x long x 12/x 

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



Megapogon orispatus.* 



(Plate XXVIL, Fig. 2, an.l Plate XXXVlll., Figs. 131-13G.) 



Thei'e are four specimens of this new species in the collection, all found together. 

 The sizes are 9 mm. x .3 nun. ; ('. mm. x 2 mm. ; (> 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 



* Criapaius, curly-haiivtt. 



2 N 2 



