NO. 2247. SPONGES FROM NORTHWESTERN PACIFIC— HOZAWA. 535 



compressed tubular form, gradually narrowed toward the base and 

 showing at the upper truncate end an oval osculum provided with 

 a weakly developed collar. The dermal surface is nearly smooth or 

 slightly hispid. The gastral surface is distinctly echinated by the 

 projecting apical rays of gastral quadriradiates. 



The largest specimen (pi. 84, fig. 8), which I have selected as the 

 type (Cat. No. 9188 U.S.N.M.), is 52 mm. long, 7 mm. broad in the 

 middle and 4 mm. broad at base. The sponge wall is about 1 mm. 

 thick. The osculum is 4 mm. long and 2 mm. wide. The color in 

 alcohol is grayish white ; the texture pretty firm. 



Structure. — Dermal and gastral cortices are pretty well developed, 

 containing some quantity of mesogloea. The former is slightly 

 thicker than the latter. The canal system is of the syconoid type. 

 The flagellate chambers are arranged radially around the gastral 

 cavity. They are straight, circular in cross-section, nearly equally 

 wide in all parts, unbranched or very slightly branched, and open 

 either separately or several together through an exhalant canal into 

 the gastral cavity. Further details concerning the soft parts could 

 not be ascertained owing to the bad state of preservation. 



The dermal skeleton is composed of triradiates which are either 

 tangentially or more or less confusedly arranged in several layers. 

 Oxea in sparse distribution project to a slight degree and nearly 

 vertically from the dermal surface. The tubar skeleton is of the 

 many-jointed articulate type. The gastral skeleton is made up of (1) 

 the paired rays of subgastral triradiates, (2) gastral triradiates 

 occuring generally in groups and with downwardly pointed basal 

 rays, (3) gastral quadriradiates with their prolonged apical rays 

 projecting into the gastral cavity, and (4) the small quadriradiates 

 which surround the exhalant canals. The skeleton of oscular collar 

 consists of oxea in two kinds and of triradiates and quadriradiates, 

 all being closely set together. The last named two kinds of spicules 

 have basal rays directed downwards. 



Spicules. — Dermal triradiates {a) slightly sagittal or subregular. 

 Rays equally thick, straight and gradually tapering to sharp point, 

 not lying in the same plane but directed slightly inwards, 80-160/x 

 long and 12-16/* thick at base. 



Tubar triradiates {h) sagittal. Rays straight, sharply pointed, 

 nearly equally thick, not lying all in one plane. Basal ray about 

 one and half as long as paired ray, 130-160 [x long and 12 [a thick 

 at base. Paired rays nearly equal, 70-90 ^ long and 12 \x thick at 

 base. 



Subgastral triradiates (c) differing from the tubar triradiates 

 only in having more widely open oral angle. In a typical example, 

 basal ray 180 (x long, paired rays 100 [i long, all 12 [x thick at base. 



