NO. 2247. SPONGES FROM NORTHWESTERN PACIFIC— HOZAWA. 555 



which I base the further description, was obtained off Cape Monati, 

 Bering Island (station 4792). It is a solitary person of an irregu- 

 larly bent and strongly laterally compressed tubular shape. The 

 osculum at the upper end is surrounded by a thin undulating oscular 

 margin. The narrowed inferior parts of the body are provided 

 with a number of irregularly shaped processes for attachment. 

 Total length of body about 140 mm., greatest breadth about 30 mm., 

 and the wall about 3 mm. thick. The dermal surface is nearly quite 

 smooth. The gastral surface is also smooth, though not even, being 

 perforated by exhalent apertures of varying size (50/^-303 mm. 

 wide). The dermal surface appears white, and the chamber layer 

 also the gastral surface grayish. The dermal cortex is rigid and 

 elastic, and may easily be sparated from the chamber layer, which 

 is very soft. 



Structure. — The canal system is of the leuconoid type. The cham- 

 ber layer is strongly lacunar, being traversed by well-developed 

 inhalent and exhalent canals. Between these canals are thickly 

 packed together the ovoid or spherical flagellate chambers of 60- 

 100/x diameter. The exhalant canals unite into tolerably wide trunks 

 which open into the gastral cavity. The latter is rather narrow. 



The dermal skeleton is well developed, composed as it is of tan- 

 gential triradiates and microxea. The triradiates are arranged in 

 several layers with basal rays directed downward. The microxea are 

 very closely set all over the dermal surface but leaving meshlike 

 pores of inhalent canals measuring 50-100/x across. The skeleton 

 of the chamber layer is made up of a confused mass of microxea 

 and of very large quadriradiates irregularly scattered among the 

 former. The gastral skeleton is formed solely of microxia disposed 

 in a dense layer; only occasionally the quadriradiates of the chamber 

 layer join the gastral skeleton with their apical rays which project 

 into the gastral cavity. The oscular fringe is supported by irregu- 

 larly and closely set microxea and triradiates, with an admixture of 

 oxea occasionally occurring in longitudinal disposition. 



Spicules. — Dermal triradiates sagittal. Rays nearly equally thick, 

 straight, sharply pointed, lying in the same plane. Basal ray dis- 

 tinctly shorter than paired rays which are strongly divergent. 

 Basal ray 450-950/x long and 50-70/a thick at base. 



Quadriradiates of chamber layer sagittal, very large, variable in 

 size, with rays of nearly equal thickness and slightly irregular out- 

 line. Basal ray straight, shorter than paired rays, 0.3-1.27 mm. 

 long and 100-150^i thick at base. Paired rays usually equal, some- 

 times unequal, either curved simply forewards or showing double 

 curvature, in the latter case curved distinctly forewards in the prox- 

 imal parts and slightly backwards in the distal parts, 0.9-2 mm. 

 long and 100-150)« thick at base. Apical ray shorter than basal ray, 

 straight or slightly curved, 350-850/x long and 100-150/x thick at base. 



