100 I. IJIMA : HEXACTINELLIDA. I. 



The gastralia — slender-rayed peiitactins of medium size — 

 are quite like the ordinary dermalia. The paratangential rays, 

 140-200;« long, are often bent and of unequal length in the same 

 spicule. The distad directed, unpaired ray is straight and 

 frequently more than thrice as long. The gastralia are rather 

 isolated in their distribution, especially so on the inner surface 

 of the excurrent canals, in which they receive the name of 

 canalaria (PL IV, fig. 28). 



The ßoricomes (PI. IV, fig. 10) are very common, but less 

 so in the elevated regions of the parietal ledges than in more 

 depressed parts. They occur both subdermally and at the apex 

 of dermal hilt-rays. Diameter 70-80 /j. ; principal rays under 

 6 /^ in length as measured from the central point of the rosette. 

 The number of terminals in a perianth varies from 9 to 12. 

 Marginal teeth of the terminal plate are well developed ; 3-5 in 

 number. 



The oxyhexasters (PI. IV, fig. 17) are much less numerous 

 than the floricome. They occur both subdermally and subgastrally. 

 Occasionally I have met with some lying outside the layer of 

 dermal paratangentials. They are least numerous, even rare, in 

 the ledges. At certain other places, as, e.g., near the parietal 

 oscula or in the subgastral region, they are tolerably common. 

 Diameter 75-83 /^ Each short and thick principal ray bears 3 or 

 4, sometimes only 2, diverging terminals. The latter moderately 

 strong, smooth and nearly straight or only slightly bent. 



The graphiocomes (PL IV, fig. 19 ; see also fig. 28) are 

 probably the commonest of all the hexasters. They occur in all 



