230 I. IJIMA : HEXACTINELLIDA. I. 



Among the pareuchymalia there also occur not jnfrequently 

 smooth oxyhexaciins of comparatively large or medium size. 

 The rays are subterminally rough-surfaced; up to about l7/<iii 

 thickness near the base ; varying in length not only in different 

 spicules but frequently also in tlie same spicule. Such a paren- 

 chymal oxyhexactin frequently occurs in the choanosome without 

 apparent definiteness as to the orientation of its rays in relation 

 to other skeletal parts. Sometimes however, there have been 

 found some -whose size, shape and situation, suggest that they are 

 reserves, as it were, of certain dermalia. They seemed to require 

 only to be pushed out more or less, in order to be classed with 

 the dermalia. On the other liand, there are occasionally found 

 similar oxyhexactins participating with one of the axes in the 

 formation of a parenchymal strand. The said axis may then be 

 greatly prolonged in excess over the other two. I think I may 

 say that the oxyhexactins represent an intermediary between the 

 dermalia and the diactins which make up the main contingent 

 of the parenchymalia. 



Characteristic of the species is the abundant occurrence of 

 a kind of intermedial parenchymal oxyhexactins, which, for the 

 sake of reference, may be called the microxyhexactins (PI. VIII, 

 figs. 24-26, 32), This is exceedingly variable in size but on the 

 whole it is small, usually measuring 175-300 /•(, sometimes only 

 110 /«, in axial length. The rays are 4-8 /i, rarely as much as 

 20/«, thick at base; straight; attenuating to a fine point. They 

 are invariably characterized by having the entire surface beset 

 with numerous, vertically out-standing, minute prickles. The 

 prickles are more pronounced in some cases than in others and 

 are decidedly spiny. The axial filament in each ray reaches 



