286 ART. 7. 1. IJIMA : HEXACTINELLIDA, IV. 



appearance with those occurring in the peripheral parts of the 

 larger specimens, though the terminals numbered usually two to 

 each principal. 



The discoctasters (PL XXII., figs. 9 and 10) are met with 

 in fair abundance in all parts of the wall, though much less 

 numerously than the oxyhexasters. They occur most abundantly 

 in the endosome, in which they may nearly equal the number of 

 the meshes in the gastral lace work ; on tlie other hand, they are 

 found but rarely, if at all, in the ectosome. Of all the Acan- 

 thascinie known to me from the Sagami Sea, this species has the 

 smallest discoctasters. Diameter, 7(3-110/^ (on an average 91/^). 

 Thus, they are in general smaller than the oxyhexasters. The 

 central node exhibits the six hump-like tubercles more or less 

 prominently developed. The principal is about one-fourth, or 

 more commonly somewhat less than one- fourth, of the length of 

 the entire ray ; it is longitudinally ribbed and uneven in contour, 

 being thicker in some parts than in others. The slender terminals 

 number 6-12 to each tuft; they are arranged not in a circle but 

 in a- solid bundle. The tuft widely expands distally since the 

 tei-minals are bent outwards. A tuft measuring 7^ ,« across at base 

 may be oO // wide at tlie outer end. The terminal discs are 

 minute and })inhead-like. Sometimes they may show 7 or 8 

 recurved marginal teeth when examined under a very high power 

 of the microscope. 



Now" and then there occur discoctasters in which some primary 

 terminals stand out free from the central node, without combining 

 with any of the eight secondary })rincipals. 



Both in size and shape the discoctasters of the species seem 

 to most closely resemble the same of B. iener F. E. Sch. Their 



