288 r. ijiMA : hexactinellida. i. 



the substratum, there is the usual reticular plate. This is thin 

 and lias small roundish meshes, measuring 20-40 /i across. 



Scattered among tlie parenchymal megascleres are found 

 small, slender-rayed and spinous oxyhexactins (sometimes oxy- 

 pentactins by suppression of a ray). (PI. XIII, figs. 18, 19). 

 Doubtless we have here the same intermedial microxyhexactin 

 which is known from Regadrella ohinoseana (PL VIII, figs. 24- 

 20), Twgeria j^uJchra and D'lclyaulus elegans. The spicule in 

 question generally measures 190-260 /^ in axial length, the rays 

 being only about 4/< thick close to the base. Numerous small 

 spines beset the entire length of the rays ; they are directed 

 somewhat obliquely outwards, though tliere exist others which 

 stand out nearly or quite vertically. They become obsolete to- 

 wards the finely pointed ends of the rays. The oxyhexactins 

 thus characterized are not very numerous in the stem or in the 

 branches. They occur in greatest abundance in the upper super- 

 ficial Layer of the basal disc. 



The (lennalia (PI. XIII, figs. 0-9, 21) are exquisitely sword- 

 like hexactins which are closely and rather indisciiminately set 

 together, so that the paratangentials of separate dermalia do not 

 form a regularly meshed latticework nor are they arranged all 

 in the same level. They vary considerably in respect of size and 

 of the relative development of their several rays. Those of the 

 larger size measure 1 mm. or somewhat more in total length, the 

 proximal blade-ray being five or six times as long as the distal 

 hilt-ray. Such a large size is attained especially by those der- 

 malia which enter into the composition of the wall of the wart- 

 like tubercles. This reminds us of the tubercles of similar 



