298 



ERYLUS ROTUXDUS. 



11-13, 16b) are more numerous than the sharp-pointed amphioxcs. Some 

 of the amphioxes, this was particularly observed in form B of var. typica, appear 

 as amphistrongA-Ies, the blunt ends of which are surmounted by small conical 

 tips. These tips may be simple or teiTaced, telescope-like. Angularly bent or 

 branched rhabd-derivates have cliiefly been observed in furni A of var. maja- 

 rhabda and in var. cidaris. The spicules of this kind in the last-named variety 

 appear as transitional forms connecting its aster-like rhabd-clusters with the 

 ordinary rhaljds. 



The dimensions of the rhabd megasdercs and the relative frequency of the 

 sharp-i)ointed and blunt ampliioxes and ampliistrongyles in the different forms 

 and varieties are tabulated below. 



