532 PROCEEDINGS OF THE NATIONAL MUSEUAI. vol.54. 



is nearly smooth though not quite even. The gastral surface appears 

 slightly hispid, due to the projecting apical rays of gastral quad- 

 riradiates. The color in alcohol is grayish white. The texture is 

 pretty firm. 



Structure. — The canal system is typically syconoid. The dermal 

 cortex is rather thin, the gastral cortex thicker. Flagellate chambers 

 are radially arranged around the gastral cavity. They are cylin- 

 drical, almost straight, slightly narrowed distally and scarcely 

 branching. Each flagellate chamber communicates with the gastral 

 cavity by means of a very short exhalant canal. The meshes of the 

 lace work formed by the gastral spicules constitute the openings of 

 exhalant canals into the gastral cavity. They are angularly cir- 

 cular or oval with a diameter of about -J mm. 



The dermal skeleton is made up of oxea and of the paired rays of 

 subdermal pseudosagittal triradiates. The oxea run somewhat lon- 

 gitudinally in a few layers, parallel to the surface. There may occur 

 very slender hair-like oxea grouped into small sparsely distributed 

 tufts, which project on the dermal surface. The tubar skeleton is 

 composed of the centripetal basal rays of subdermal pseudosagittal 

 triradiates, of the centrifugal basal rays of subgastral sagittal tri- 

 radiates, and of tubar triradiates which are placed in several layers 

 between the spicules just mentioned. The gastral skeleton consists 

 of the paired rays of subgastral sagittal triradiates, of gastral tri- 

 radiates arranged in several layers, and of a small number of gastral 

 quadriradiates, the apical rays of which project into the gastral cav- 

 ity pointing upwards. The basal rays of gastral tri- and quadri- 

 radiates are directed towards the sponge base and are grouped into 

 bundles. The skeleton of the oscular margin is a close-meshed retic- 

 ulum formed by fine longitudinally disposed linear spicules and by 

 triradiates with strongly divergent paired rays. 



Spicules. — Subdermal triradiates (a) pseudosagittal, irregular. 

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

 not lying in the same plane. Basal ray longer than paired rays, 

 usually nearly straight except for a slight curvature at base, some- 

 times crooked, 140-240[;. long and 12[ji, thick at base. Paired rays 

 unequally long and differently shaped. The longer ray nearly twice 

 as long as the shorter, doubly flexed, curving first backwards and 

 then slightly forewards, sometimes crooked, 100-160[jl long and 12[i, 

 thick at base. The shorter ray not straight, being distinctly curved 

 in the middle parts, 60-80[jl long and 12[jl thick at base. 



Tubar triradiates (h) sagittal, more or less varying in size and 

 shape. Eays nearly equally thick, gradually tapering to sharply 

 pointed end, not lying in the same plane. Basal ray distinctly or 

 sometimes only slightly longer than paired rays, straight, l70-290[ji. 

 long and 12[x thick at base. Paired rays slightly curved, rather 

 irregular in outline, lOO-lOOjx long and 12[;, thick at base. 



