W) 



adjoining sketch Fig. 13 (which was not drawn with the 

 camera). I may state thai I found the same pecuhar 

 membrane-lormalioii in .S7/. drobdchiensis (by a fertil- 

 ization made al llie same lime, which, however, did 

 nol lesiill in any rearing of I lie larva', I he breeding 

 season of llial species being then already pasl, only 

 few eggs remaining); I regret not having noticed whether i-Ik. i.{. Egg in the 



,, ' , ' ■ f/ I I • l-c-cll stage of Sir. 



the same r)lienomeiion occurs in Sir. niilcnerrimiis. , , 



' • /raiiiificanus: show 



The gaslrula slage was reached after about 21 hours, iny douhio iiicm- 

 and in the course of the next day the embryos had braiu-. 



assumed I lie shape of young Plutei. The poslero-dorsal aims began to 

 appear al llie age of 8 days. Beyond lliis stage 1 did not succeed in 

 rearing the larvte, the culture dying oil when Ihe larvae were 12 days 

 old. .\ new fertili/.alion was tried in the laler pari of .June, but then 



Ihe breeding season was pasl and only few 

 eggs could be found, which did not develop 

 normally. However, 1 can give some informa- 

 tion also of the fully formed larva of Str. 

 /idnriscaniis, having found a s|)ecimen in the 

 plankton. As no other species of FLchinoids 

 occur there, besides Dendraster excentriciis — 

 the larva of which 1 have also reared, and 

 which has no resemblance to the present larva 

 — and a Spatangoid, Brisaster latifrons (A. 

 Ag.) — which was not ripe and which has, 

 moreover, probably not pelagic larva — there 

 cannol be any doubt Ihat this larva really 

 belongs to .S7/. franciscanus. 



The larva of S. franciscanus in its first stage 

 difTers from that of drohachiensis and pukher- 

 rinms in Ihe posterior end of its body being 

 distinctly less elongaled and more rounded 

 (PI. IX, Figs. 1 — 3). The arms are nol so broad 

 as in the said species. As in these species the 

 body skeleton does not form a basket struc- 

 ture. The body rod is clubshaped, rather 

 strongly thorny at the thickened end, which 

 curves somewhat inwards; it is distinctly 

 Fig. 14. Skeleton of larva of shorter than in the two other species. Further- 

 „ , CI 100/ more this larva diners from the two other 



stage. Side view. '"7,. 



Letters a.s in lig. ."). larvae kuown of Ihis genus in having a well 



7 



