552 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.54. 



height ; it leads into a wide gastral cavity. The sponge wall is about 

 9. mm. thick in the middle parts of the body. The color in alcohol 

 is grayish-white and the texture moderately firm. 



/Structure. — The canal system is of the leuconoid type. The dermal 

 pores, thickly distributed all over the surface, lead into narrow canals 

 which soon join together to form very wide inhalent canals run- 

 ning deep into the wall. The exhalant canals are also very wide and 

 originate from deep parts of the wall. The apertures by which they 

 open into the gastral cavity measure up to 2 mm. across. The flagel- 

 late chambers are densely and irregularly arranged between inhalant 

 and exhalant canals. They are more or less spherical, measuring 

 100-150 fi in diameter. 



The skeleton of the dermal cortex is composed of tangential tri- 

 radiates arranged in a few layers. Their basal ray is in most cases 

 pointed toward the sponge base. The large oxea which occur 

 thickly in vertical disposition in the sponge wall project out on the 

 dermal surface. Microxea are found in two kinds on the dermal 

 surface; the smaller kind is thinly scattered all over the surface in 

 tangential disposition, while the larger kind is grouped into small 

 tufts which project externally in association with large oxea. The 

 skeleton of the chamber layer consists of quadriradiates of various 

 sizes. Though seemingly irregularly scattered, the majority of 

 them have basal rays directed centrifugally, thus presenting a trace 

 of the articulate character. The gastral skeleton is very thin, being 

 made up of quadriradiates, the apical ray of which projects into ex- 

 halant canals or into the gastral cavity. The skeleton of the oscular 

 margin is composed of large oxea, microxea, triradiates and quad- 

 riradiates. The large oxea are longitudinally placed, paralled with 

 the basal rays of tri- and quadriradiates. The microxea are thinly 

 scattered on the outer surface. The tri- and quadriradiates have 

 very strongly divergent paired rays which stand nearly at right 

 angles to the basal ray. 



/Spicules. — Dermal triradiates (a) slightly sagittal, with rays 

 sharply pointed and lying in the same plane. Basal ray nearly 

 straight, usually slightly shorter and broader than paired rays, 

 250-400/x long and 20-24)w thick at base. Paired rays equal or slightly 

 differentiated in length, slightly curved forewards at base and 

 nearly straight or slightly curved in the remaining parts, 270-440/* 

 long and 16-20/x thick at base. 



Quadriradiates of chamber layer (h) slightly sagittal. All rays 

 nearly equally thick and sharply pointed. Basal ray straight, 

 300-450/* long and 32/i thick at base. Paired rays slightly curved 

 forewards at base and nearly straight or slightly curved backwards 

 in the remaining parts, more or less irregular in outline, 300-450/* 

 long and 32/* thick at base. Apical ray much shorter than facial 

 rays, slightly curved. 



