NO. 2247. SPONGES FROM NORTHWESTERN PACIFIC— HOZAW A. 



541 



while the apical rays project into the gastral cavity. The skeleton 

 of the oscular margin is formed of two kinds of oxea forming a 

 fringe and of very closely set triradiates and qiiadriradiates, both of 

 which have very strongly diverging paired rays, the basal ray being 

 directed downward in a regular manner. 



Spicules. — Dermal triradiates {a) slightly sagittal, slender rayed. 

 All rays nearly equally thick, tapering gradually to sharp point. 

 Basal ray straight, slightly longer than paired rays, 140-240 ju, long 

 and 8-10 fx thick at base. Paired rays nearly equal, straight or slightly 

 curved backward, 110-200 ]x long and 8-10 ^ thick at base. 



Subgastral triradiates {h) strongly sagittal. All rays nearly 

 equally thick, lying in one plane. Basal ray straight, tapering to 



Fig. 6. — Achramoepha diomediae. a, dermal triradiates. t, subgastral trira- 

 diates. C, gastral QUADRIRADIATES. d, TRIRADIATE of oscular margin. e, QUAD- 

 BIRADIATE OF OSCULAR MARGIN. f, OXEA PROJECTING FROM DERMAL SURFACE. (J, OXEA 

 OF OSCULAR MARGIN. All X 150. 



fine point, 200-310 fi long and 8-10 u thick at base. Paired rays 

 strongly diverging, equal, nearly half as long as basal ray, curved 

 backward at a point nearer the base than the sharply pointed end, 

 100-150 jLi long and 8-10 jx thick at base. 



Gastral quadriradiates (c) sagittal. Basal ray straight, much 

 longer and slightly thicker than paired rays, 200-250 ^ long and 

 10-12 iJi thick at base. Paired rays equal, doubly curved, ending in 

 sharp point, 110-150 ii long and 8-10 ix tliick at base. Apical ray 

 curved forward, tapering from base to very sharp point, about 100 ju. 

 long and 8 fi thick. 



Triradiates of oscular margin {d) strongly sagittal. Basal ray 

 straight, sharply pointed, slightly longer and distinctly thinner than 

 paired rays, about 250 fi long and 12 /* thick at base. Paired rays 



