48 



longing U) Ihis same larva I have shown in my 'iM-hinodornuMi-Larven 

 <i. Planklon-h",x]n'(liti()M' (p. 1)1) that he made a mistake, 'i'liese larviP, 

 which were canghl IVce swimming;, evident ly belong to a (",ly|)easlroi(l, 

 most prob;il)ly lu-hinnKtchniiis jxtrnid^). \>u\ tlie main thing is that they 

 are not .S7/. (Inibdchii'usis, and his slatomenl ol' the presence of vibratile 

 opanlels in the SlroiniiilotriUrolus-hwyix lluis lacks real loiindation. 

 Hereby 1 do not mean to ascertain that there aie no epanlels in the 

 .S7/-. diob(trhicnsis-\aryii. On the contrary, I may lake the ()p|)orlnnity 

 here to stale thai the Sir. dioha(lu('nsis-]a\\i\ has not only the nsnal 

 e|)aulels. bnl it has also a posterior |)air o! large epanlets, ninch as 

 in the larva of lulunus csculcnlus. This statement rests, no! npon the 

 reai-ing ol' this larva, of which 1 have not as yet fonnd an ojjportnnitw 

 bnl on the evidence of a ])air of sjiecimens fonnd in a i)lankton-sam|)U' 

 from (ireenland, taken by Mr. K. Slephensen in l)re(lelior(l. Sonlh 

 Greenland, in Ihe sunimcr of 1912. As .S7/'. drolxirliiciisis is the only lit- 

 toral I'k'hinoid of (ireenland there can be no donbt that the larva belongs 

 to this species. I'nforlnnately the specimens are in a rather poor slate 

 of preservation, so that they are not fit for being figured; but the epanl- 

 els are distinct enough. It is a |)ity thai the larva of .S7/'. piilrhrr- 

 rimus could not be reared to metamorphosis so that the question whether 

 it has epaulets like drobachiensis could be decided, lint in view of the 

 complete accordance with the drobachiensis laiva in the earlier stages 

 there is every reason to expect that it will also prove to have epaulets 

 in the same wav as Ihat larva. 



Strongylocentrotus franciscanus (A.Ai^.). 



I'l. IX Figs. 1- -4. 



The development of this species I had the opportunity of studying 

 while slaying at the Biological Station at Nanaimo, Vancouver Isl., 

 B. C, in May — .June 1915. Fertilization was made on May 26th. The 

 eggs are small and transparent. I noticed the peculiarity that there is 

 found a double fertilization membrane, the outer one standing far out 

 from the egg, while the inner membrane lemains close to the surface 

 of the egg and follows the outline of the cleavage cells, as shown in the 



') h) the work qiioted 1 liave sii<;fJustiMl llial tlicy iiii^lil pcrlmps l)('l(m}< to MilliUi lislii- 

 (liitata, pointin}>, however, also to their likeness to the E(liiiiurutliniii.s-h\r\d. .Mae Bride 

 ill his Memoir on the I^evelopnient of Echinus esculenlus (Philos. Transact. B. Vol. lO.*). 1903. 

 p. 287) still states that by this work of Agassi/, ''for the first time a complete history of 

 the changes in external form undergone in a single species was obtained ". I-Aidently Mai- 

 Bride nnisl have overlooked my criticism of Agassi/' work, llic honour ol having lor the 

 (irst time given the couLplele history of the development of an Kchiriold (regarding the ex- 

 ternal form) belongs to Thiel (Hchiiwcyanms), not lo Agassi/. 



