50 AET. ]. — I. IJIMA : HEXACTINELLIDA, III. 



hypodermalia ; they are themselves but little specialized from the 

 parenchymal oxyhexactins. It may be said in general that in 

 length of rays they are about equal to the larger oxyhexactins 

 of the parenchyma in the same individual. In most of the 

 different individuals examined, I have found the length of the 

 cruciately disposed paratangential axis to fluctuate between 500 /^ 

 and 800 jj- ; in the large specimen (No. 434) from Onigase, the 

 same axis reaches up to le mm. in length and 20/^ in breadth of 

 ray near the central node. The unpaired proximal ray is always 

 longer than, and often fully twice as long as, the paratangential 

 of the same spicule ; it is always straight and dips inwards, 

 generally in association with the radially directed axis of a 

 parenchymal oxyhexactin. The paratangentials, as seen in surface 

 view, are straight ; the latticework formed by them is on the 

 whole irregular, though in places an aj^proach is shown to the 

 formation of rectangular meshes. In lateral views the paratan- 

 gentials are either likewise straight or so curved as to accommodate 

 themselves to the curvature of the external body-surface. As in 

 parenchymal oxyhexactins, the rays taper towards their ends, 

 near which the otherwise smooth surface is more or less roughened 

 by the presence of obsolete microtubercles. 



The ff astral oxyhexactins, already described in passing, occur 

 in abundance on the interual surface, without however showing 

 any definite order in their relations with one another or forming 

 a distinct layer by themselves. Exactly similar oxyhexactins 

 often occur also as canalaria along the lumen of excurrent canals. 



The basidiclyonal plate or mass is composed, as usual, of 

 synapticularly fused, thick-rayed hexactins, the rays of which are 



