229 



Ophioiieiris sijiKtmulosa (aiul doubtlfss many ollu-r ()|)liiuri(ls), in wliich 

 also Iho larval ski'lcton lias (iisa])i)oare(l compk-U'ly. no Iract- ol' llic I'lii- 

 leus-fonii iTmaiiiiiii». In llu'se lallcr larva' ciliali'd rings are lornu-d. as in 

 the barrel-shaped larva' of (loniatulids and Dendrochiroles. and in the 

 pupa-slage of other llololhurians. 



The existence of a true pupa-stage in Ophiurids was first shown by 

 Caswell (irave')- (Very likely the larva, in which the rearrangement of 

 the vibratile band into an indication of rings was observefi by (irave, was 

 a species of the type described here as Ophiopluleus opulcnlus). My own 

 observations in Ihe main agree with those of (irave, iiowever, difTering 



Fig. 102. A. Ophiopluleus Mflsrhnikojfi (after Met sell n iko ff); B. Ophiopl. Clupitrrdci (after 

 Claparede: iiiodilied so as to rejjreseiil the larva in ventral view); (;. Ophiopl. clont/uliis 



(after K ro li n). 



from them in some iiiiiioi |)()iiils. 1 liiul the rings less distinctly indicated 

 than shown by (liave. which may, however, be due lo m\ not having ob- 

 served the metamorphosing larvae in the same lateral position as that in 

 which they are represented in (1 rave's fig. (S. but from the venlial or dorsal 

 side. The anterior ■ring" 1 have not found lo be complete, but it may very 

 well be so in a later stage of metamorphosis such as that figured by (irave. 

 the stages in which 1 have noticed this rearrangemenl of the vibratile i)and 

 being less advanced (PI. XXIX, Fig. 3; PI. XXX. l*'ig. 2). 1 have been 

 able to ascertain thai Ihc anterior band of the ■i)upa"'-slage is derived 

 directly from the i)reoral band of the larva. .Vnolhei- interesting fact is 

 that in some cases, at least, the vibratile band of the posterolateral arms 

 in an advanced stage of metamorphosis coalesces in the midline of the 

 larval body, ixlow (he developing 0])hiuiid: how far this is a general rule 

 remains to be ascertained. 



') (Caswell (irave. On the occurrence among Kcliinodernis of larv;e with liUa arranged 

 in transverse rings, with a suggestion as to their significance. Biol. Bulletin. V. \W.i. p. 175. 



