52 I. IJIMA : HEXACTINEELIDA. I. 



of importance in the systematic of the genus, save that their 

 size has in certain cases been found to be of use in the specific 

 distinction. 



The place and manner of origin of the floricome as well 

 as its subsequent history seem not to have been followed out 

 with accuracy by previous writers. It arises among the external 

 trabecule beneatli the dermal latticework. At a certain stage 

 of its development, the terminals are short and exceedingly fine 

 (PL II, fig. 10, PL IV, fig. 11 ; &c.). By the time the perianths 

 have reached the definitive shape and size by the elongation and 

 flaring out of the still slender terminals, the entire rosette is of 

 the form which has been called by F. E. Schulze the sigmato- 

 come (PL II, fig. 11 ; PL IV, fig. 12) and which he has apparently 

 taken for a separate category of hexasters in E. regalis (19', p. 28). 

 The distal portion of the terminals continues to thicken ; then, 

 the rudiment of the terminal disc is formed (PL II, figs. 12, 14 ; 

 PL IV, figs. 13, 14), which stage in the development of the 

 floricome has already been recognized by F. E. Schulze in E. 

 aspera and Didyaulua clegans ('95, pp. 29, 41). However, that 

 writer seems not to have observed its much earlier stage in which 

 the terminals are still quite short, and evidently on that account, 

 it appeared to him that all the radial rays attained their full 

 length, though much more slender at first than in the later state, 

 immediately upon their origin {I.e., p. 41). This is at any rate 

 not quite true with the terminals of the floricome. They do 

 grow gradually in length during their development, an obser- 

 vation which I have found perfectly corroborated in the 

 development of the graphiocome also (PL V, figs. 32-34). 



The floricome, after the complete development of its parts, 

 seems not to be destined to remain at the locus nascendi but to 



