14 ART. 7.— I. IJIMA : HEXACÏIXELLIDA, IV. 



Structurally and in appearance the rosette is quite similar 

 to the same of Synipagella (Contril). III., ]^. 106). The hemi- 

 spherical knob, bearing the featlier-duster-like bunch of delicate 

 terminals, usually shows at the center of the convex outer surface 

 a small process, into which the axial filament is seen to extend 

 itself. The process tlien is a direct continiuitioii of the principal and 

 represents the outer end of the primary ray of a hexactin ; the 

 terminal-bearing knob and the terminids with it are then to be 

 considered as secoJidary structures that have developed along the 

 course of a primary my, not at its outer end. This may l)e held 

 as an indication that the strobiloplumicome is a hexaster swi _y<?/^cr/>;, 

 having arisen independently of the ordinary discohexaster and 

 oxyhexaster in which the terminals a])pear to be ah origine at 

 the very ends of primary hexactin-rays. 



The central process aljove I'eferred to may be mure or less 

 atrophied and may even disappear altogether. Thus, several 

 instances in the present species have come under my observation 

 in which the process was reduced to a mere acuminous })oint, 

 the entire knob in shape presenting a resendjlance to an acorn. 

 In some other exce])tional cases I have convinced myself, as I 

 did also with some of the same rosettes in Syiiipagella anoniala, 

 that the central process was totally wanting. 



Soft Parts. 



All that I have observed as regards the soft ])a]-ts of tliis 

 sj)ecies may be referred to in l)rief. 



In iig. *•>, PI. 1., the soft parts are shown as seen in a 

 section under a low power of the microscope. The shading given 

 to the chaujl)ers is somewhat artificial. With respect to fig. 10, 

 which is meant to illustrate the highly inagnified appearance of 



