12 ART. 1. — i. IJIMA: HÉXACTiNELLlDA, lit. 



fascicles there are none Avhicli, on account of a specially einpliasized 

 size or strength, may be distinguished as the principalia. Nor 

 does there exist synaptieular fusion among any of the paren- 

 chymalia, so far as those of the main body are concerned. — 

 Besides the diactins there also exist, among the parenchymalia, 

 a number of medium- sized hexactins in sparse distribution (see 

 lig. 15). Occasionally these are represented by forms more or 

 less closely approaching a pentactin or even a stauractin in form. 

 Axial length up to nearly 1 mm.; thickness of rays near base up 

 to 20 /^ ; the rays gradually taper towards the free end, which is 

 faintly rough-surfaced and either sharply or l)luntly pointed. 

 The rays in a spicule are often of unequal lengths. In some 

 cases one of the axes was found to be prolonged more or 

 less in comparison with the rest, and with that elongated axis 

 the spicule took part in the composition of a parenchymal 

 fascicle ; but the rule is that the hexactins stand in no delinite 

 relation with other parenchymal spicules as regards the situation 

 of their rays. 



The parenchymal hexactins are, in point of size and shape, 

 not always shar]:)ly distinguishable from those hexactins which 

 may be called the canalaria. These are found sparingly and 

 isolatedly in irregular distribution on the canalar surface as well 

 as on the hypodermal beams of the frontal lattice. Two of them 

 are seem in the lower part of fig. 13, PI. II. They are re- 

 cognizable as such only when one of the six rays is considerably 

 shorter than the rest and projects freely, from l)ase to tij), into 

 the canalar lumeii or the subdermal space. The free ray shows, 

 though not always, a further specialization in that it has a 

 rounded termination, instead of being jiointed like the other rays. 



