36 ATA\ 1. — I. IJIMA : HEXACTINELLIDA, III. 



ai^pear as indistinct minute spots beneath a thin and clear dermal 

 layer. On the gastral side the excurrent canals open apparently 

 directly into the cavity ; many of the openings are considerably 

 larger than the incurrcnt canalar a])ertures seen on the outside. 

 The sponge is soft and delicate in texture. In all essential points 

 of the spiculation the two specimens agree closely with each 

 other. 



In view of their small size, I at first considered it possible 

 that these were young specimens, but the presence of large 

 archœocyte-congeries in both and the discovery, in one specimen, 

 of larvse which apparently belonged to it, decidedly support the 

 view that thev are mature and fidl-grown individuals. 



Spiculation. 



The parenchymalla, forming the main framework of the 

 sponge-w^all, are for the most part legular oxyhexactins of 

 moderately large size ; diactins occur in a relatively small number. 

 The oxyhexactins have straight tapering rays which may reach 

 nearly half a millimeter in length and 10 f- in thickness close to 

 the central node. There are all sizes leading down to the 

 dimensions, given later, of those oxyhexactins which I consider 

 as gastralia. The rays appear smooth under a low magnification 

 but are in fact insignificantly rough-surfaced on account of minute 

 tubercles occurring at rather wide intervals all over them. The 

 o-eneral manner of arransrement of the hexactins in relation to one 

 another is such that, while being disposed in several layers with 

 one axis directed radially, they have each of the rays placed, for 



