4 ART. 5. — SANJI HÖZAWA : 



roundish mass, measui'ing about 15 mm. in height and 30 mm. in 

 maximum diameter. On the whole, the oscular tubes are much 

 smaller than those of any other specimen. The largest tube meas- 

 ures only 5 mm. long and 2 mm. broad in the widest part, where 

 the wall is nearly 0.45 mm. thick. The osculum is irregularly 

 circular, measuring about 0.45 mm. in diameter ; oscular fringe of 

 oxea not visible with the naked eye. 



The following description of canal system and spicules is 

 "based on studies of the type- specimen. 



Canal system (PI. n., figs. 10, II). 



The canal system is typically syconoid. Dermal pores, 40- 

 100 fji in diameter, are scattered irregularly over the sponge 

 surface. The dermal cortex is rather weakly developed with a 

 small quantity of mesoglœa. Tlie flagellate chambers are straight, 

 cyhndrical and usually not branched ; they are radially arranged 

 around the gastral cavity, extending from gastral to dermal cortex. 

 Each chamber is provided with a number of small prosopyles of 

 10-40 /'- diameter, and with a single apopyle at the inner end. 

 The position of nucleus in collar cells is apical. The gastral cortex 

 is nearly as thick as the dermal and is perforated by short but 

 rather wide exhalant canals, which usually arise each from a 

 single chamber and sometimes from two or three chambers. A 

 weakly developed diaphragm occurs at the apopyle. Diameter of 

 exhalant pores 70-150 /a 



Skeleton (PL II., figs. 10, 11). ' 



The dermal skeleton is composed of the following elements : 

 1) triradiates, which are tangentially arranged in several layers 

 without definite orientation ; 2) the paired rays of subdermal 



