NO. 2247. SPONGES FROM NORTHWESTERN PACIFIC— HOZAWA. 547 



thick at base. Paired rays, 130-180/* long and about 20/* thick 

 at base. 



Microxea of dermal skeleton (g) slightly curved, :proximally 

 tapering to sharp point, distally terminating with a lance-head which 

 is slightly bent and provided with sharp or obtuse apex, 60-90ju, long 

 and 4-6/1 thick at head. 



Microxea of gastral skeleton exactly similar to those of dermal 

 skeleton. 



Locality. — Off Semisopochnoi Island, Aleutian Islands (Station 

 4777, 52 fathoms). 



Remarks. — This species differs from Leucandra tuba^ new species, 

 chiefly in the peculiar external form, in spiciilation and in the absence 

 of a skeleton proper to oscular margin. In external form it closely 

 resembles the members of the genus Pericharax Polejaeff. 



10. LEUCANDRA FOLIATA, new species. 



Plate 84, fig. 5. 



This new species is founded on the strength of a single specimen 

 in the collection (Cat. No. 9185, U.S.N.M.). The sponge (pi. 84, 

 fig. 5) is foliate, consisting of a single continuous lamella, which is 

 irregularly folded or convoluted. It is attached in the middle of its 

 lower surface by means of several nipple-shaped basal processes. 

 The lamella is about 55 mm. broad and about 4 mm. thick in the 

 middle parts where it is thickest. The thickness decreases peripher- 

 ally toward the very thin oscular margin. The inner surface of the 

 lamella appears smooth to the naked eye; it is minutely punctuate, 

 due to the apertures of exhalant canals, which are more distinct in 

 the middle parts than in the periphery. The outer surface is like- 

 wise smooth, but without the punctate appearance of the inner sur- 

 face. The color in alcohol is greyish white. The texture is fairly 

 compact, rigid and brittle. 



Structure. — Very wide inhalant canals arise just beneath the der- 

 mal surface and penetrate deep into the chamber layer, giving off 

 numerous branches on the way. Small exhalant canals combine into 

 a number of larger ones which open on the gastral surface by the 

 apertures above alluded to. Between the inhalant and exhalant 

 canal systems the flagellate chambers are quite irregularly scattered. 

 They are oviid or spherical, with a diameter of 50-100[;.. 



The dermal skeleton is very thin and is composed of chiefly small 

 and occasionally very large tangential triradiates, with basal ray 

 pointing away from oscular margin. The skeleton of the chamber 

 layer consists of large triradiates of a slightly variable size, which 

 are densely set together without definite order. The larger exhalant 

 canals are lined with quadriradiates, the apical ray of which projects 

 into the canalar lumen. There exists a gastral skeleton made up of 



