4 ART. 9. — I. IJIMA : HEXACTINELLIDA. 



skeletal framework, in which all the component jiarenchymalia 

 arc rigidly fused together by synapticular formations from the 

 base to the sieve-] »late inclusive. The loose parts have been 

 almost entirely lost. In this denuded state the specimen is 

 tubular and phallus-like, gradually expanding from the base to 

 the somewhat flatly rounded upper end. Total length 210 mm. 

 Cross-section of the body, which is irregularly circular, measures 

 in diameter : 64-62 z mm. near the upper end, 45-42 mm. at the 

 middle and 36-33 mm. near the lower end. 



The closed basal end is obliquely truncated. Compact 

 basidictyoDal incrustation is to be seen at this end, and also in 

 an isolated irregular patch close to, but on one side of, this end. 

 One point in the description given by Quoy and Gaimaed is 

 in disagreement with the facts. According to them the body 

 should be open at the extremity opposite to that which is dilated 

 and rounded, although they have made mention of certain indica- 

 tions that the sponge must have been fixed by one of its ends. 

 In their figure also the basal end presents the appearance of 

 being open, which is certainly a misrepresentation, probably of 

 the engraver. Probably the authors were to a degree misled 

 by this appearance of their figure. 



The upper end of the body is closed by an arching over, as 

 it were, of the lateral wall. This passes over gradually and 

 without essential change in texture into the terminal part which 

 should represent the sieve-plate. The absence of a demarcation 

 of any sort between the sieve-plate and the lateral wall has been 

 repeatedly emphasized by writers ; but, in my opinion, it is by 

 no means to be excluded that in the original immacerated state 

 of the specimen there was present a marginal ridge consisting of 

 a loose tissue such as might easily have been lost. 



