598 



s. GOTO : 



mens this tendency is carried so far and the poriferous areas are 

 so close together that comparatively little space is left between 

 them, the adjacent poriferous areas being in many cases separa- 

 ted from each other by a single row of coarse granules, which 

 again may entirely disappear. In none of these three specimens 

 can T see distinctly the arrangement of these poriferous areas in 

 the form of rosettes around a number of central non- poriferous 

 areas mentioned by preceding authors; the poriferous areas do 

 not show any regular arrangement. In the three specimens under 

 consideration, the total poriferous areas far outweigh the non- 

 poriferous. The latter also bear small forcipiform pedicellariœ, 

 which appear to vary considerably in number in different speci- 

 mens, there being sometimes several of them in one poriferous 

 area, while in other cases one has to look for them for some 

 time to find one (PL XYII, fig. 259, 2G0). 



In the three specimens in question the ventral side is entire- 

 ly covered over with coarse granules, which are not spinous. 

 The more or less spiniform coarse granules of the dorsal side 

 become rapidly rounded towards the edge of the ventral side, 

 and pass on without any sharp contrast to the coarse granules 

 of the latter. The demarcation into polygonal areas referred 

 to by preceding authors is seen in only one of these specimens. 

 The granules of the ventral side are, generally speaking, decided- 

 ly coarser near the ambulacral furrows and towards the mouth, 

 at the angles of which there are always some particularly well 

 developed granules. The spaces between the coarse granules of 

 the ventral side are covered over Avith finer granules, and the 

 areal ratio between the fine-grained and. coarse-grained portions 

 varies largely in the different specimens. In the fine-grained areas 



