106 ART. 1. 1. IJIMA : HEXACTINELLTDA, III. 



looked linder an insufficient power of the microscope, the hexaster 

 might readily be mistaken for an oxvhexaster. 



The strobiloplumicome (figs. 10 and II) is common, sometimes 

 quite abundant, in the subgastral space. In the subdermal region 

 it occurs only occasionally. Diameter, 34-64 /^ The smaller ones 

 have much finer and more delicate-looking terminals, and probably 

 represent a not fully developed state of the rosette. The knob 

 at the end of principals is hemispherical, and from its convex 

 surface arise the terminals in about four closely set whorls (fig. 

 11). As usual the terminals of the innermost whorl are the 

 longestand measure about 27/^ in length; those of the outermost 

 whorl, only about 10/^. The small central process at the distal 

 end of the terminal-bearing knob is frequently difficult to see, 

 ])ut seems to be generally present. Exceptionally was I impressed 

 of its being really absent. Under favorable circumstances I have 

 distinctly seen the axial filament go light through the knob into 

 the distal process. 



As hexasters of inconstant occurrence I consider the peculiar 

 kind of discohexaster shown in fig. 16. I have discovered it in 

 a limited number in the body of a medium-sized specimen (Sei. 

 Coll. Mus. No. 473, from Outside Okinose by the Iwado-line, 

 500 m.) together with the usual hexasters of the species. It has 

 never been met with in any other specimen. In its general 

 appearance and in the character of its terminal discs, the disco- 

 hexaster in question is not unlike certain others (fig, 17) which 

 occur in the stalk ; but the remarkable difierence consists in the 

 fact that either all or some of the terminals split into disc-bearing 

 branchlets [at a point near the outer end. Diameter, 42/-« and 

 under. Terminals, 3-4 to each short principal, rough-surfaced. 

 Branchlets, 2-5 to a terminal in an umbel-like tuft ; their length 



