38 



K. MITSUKUIU. 



enee to those perforated plates or " Hemtnuugsbildungen " which 

 others mention as an important feature. 



Stage II: — In this group, I propose to include those individuals in 

 which those small, perforated plates with or without rudiments of a 

 spire (fig. 3) begin to be a noticeable feature but not to such an extent 

 that they seem to form a larger portion of the calcareous deposits of the 

 animal than the well formed tables. I have fixed a somewhat arbitrary 

 standard and put in this group all those in whose skin I could count at 

 least 7-10 well-built tables (fig. 2) in a field, when examined with Zeiss 

 CC X 3. The tables with 2-3 transverse beams are most frequent. 

 Some with only one beam are seen. 



It is impossible to fix any limits in the lengths of individuals belong- 

 ing to this group with anything like accuracy. Those which I have 

 placed in this group are respectively 50, 50 54, 70, 70, and 110 mm. in 

 lengths. 



I believe that the single specimen which Théel identified with 

 some hesitation as Stichopus japonicus, belongs to this stage. His de- 

 scription tallies well with what I have given above. 



Stage III: — This I propose to call the typicus stage, for those speci- 

 mens which Théel distinguished as Stichopus japonicus, var. typicus 

 may be taken as good examples of this stage. Here the calcareous 

 bodies which correspond to the large well formed tables of the preceding 

 stage have begun, many of them, to show various degrees of imperfec- 

 tion. This arresting of development affects both the basal disc and the 

 spire. Thus the spire may become lower, have a smaller number of 

 transverse beams (1-2), and often have the ends of the pillars bent out- 

 wards (Selenica, Fig. 34, or Théel, pl. VIII, fig. 2b). Or the pillars 

 may be reduced in number to three or two, or be occasionally increased 

 to five (Théel, pl. VIII, fig. 2d), and often inclined towards one 

 another, especially near the upper end so as to produce a conical shape. 

 Or the spire may be represented by 1-4 simple knobs which are rudi- 

 ments of the pillars. Or finally there may be no trace of a spire. The 

 complete tables have the margin of their basal disc entirely smooth, but 



