276 AKT. 7. — I. IJIMA : HEXACTINELLIDA, IV. 



beams, 25 /^ or less in tliickness, are sparsely microtubercled and 

 contain, here and there in the nodes, axial canals in the form of 

 a plane cross. The basidictyonal hexactins are likewise sparsely 

 microtubercled. There can be scarcely any doubt that these are 

 the same as those which F. E. Schulze ('99, p. 63) discovered 

 forming a rigid framework in the buds of R. mirabilis. 



Finally it should be stated that the spicules, as might be 

 expected, are subject to certain variations according to the age 

 or the individuality of the sponge. Thus, in a young specimen 

 not larger than a nut and attached to the same piece of coal- 

 cinder as the type specimen, I find several of the spicules 

 considerably smaller than those mentioned above. They measure as 

 follows : Paratangentials of prostal pentactins not over 5 mm. in 

 length ; dermalia 275-330 /^ (on an average 320 /^) long and 

 generally about 7? /^ thick in the middle ; proximal ray of 

 gastralia 330-385 /^ long ; paratangentials of same 187-240/^ long; 

 diameter of discoctasters 143-155 /^ ; principals of same about 19 /-« 

 long ; etc. lu a certain specimen I have found the terminals of 

 oxyhexasteis sparsely microtuljercled at the base, instead of being 

 entirely smooth. 



RHABDOCALYPTUS CAPILLATUS Ij. 

 Pis. XXir. and XXIII. 



lUiabcIocalyplud capiUatus. I. Ijima, '97, p. öl. 



Of this species some sixteen specimens of various sizes have 

 thus far been examined bv me. The known localities are : 



