62 



posterior transverse rod especially indieatiiif* that it can hardly be so 

 very closely related to those forms. 



Evechinus chloroticus (Val). 



I'l. \, I'igs. 1—5. 



Duriiifi a trip round the Xmili Island of New Zealand, onboard ihv S. 

 Z. (i. S. •"liineinoa"' 1 had liu' ()i)])orlunily of rearint* the larva of this 

 s])ecies. Ferlili/alion was undertaken on the 18th of December 191 1. The 

 culture of the larva* was kepi until the 22nd of .lanuary 191.'); Ihe larva* 

 had attained their full si/e by that lime, bul metamorphosis had not 

 yet begun. The development of Ihis species then goes on rather slowly, 

 though perha])s nol finite so slowly in nature. The conditions under 

 which the cultures hail to be ke])l onboard Ihe small steamer were not 

 the very best, and this may perhai)s have had some delaying inlluence on 

 the development, as also the fact that not few of the larva? showed more 

 or less pronounced abnormalities most probably is due to some extent to 

 these conditions. The fad that the two cull ures which were made showed a 

 rather marked difference in the time of appearance of the skeleton indicates 

 that this supposition is correct. Ikit, anyhow, a good number of the larva 

 (levelo])e(l normally, and a fairly complete description of the larva of this 

 species thus can be given. — Unfortunately there was no j)ossibility of 

 making drawings from the living specimens, and moreover it happened 

 that in all the specimens of the more advanced larvae preserved the skeleton 

 had been dissolved (while the shape was preserved quite exceptionally 

 well); only in some larvae of the first stage the skeleton remained intact 

 — but all of them present some abnormalities. The description of the 

 skeleton thus cannot be quite satisfactory; but the main features at least 

 can be ascertained from Ihis material combined with the notes put down 

 after observations on the living specimens. 



The cleavage is quite regular; the 8-cell stage was reached in the course 

 of 4 hours; swimming blastula were found ca. 16 hours after fertilization, 

 and the gastrula stage was reached at the age of about 24 hours. They 

 were not very clear and evidently do not form a very good object foi- mi- 

 croscopical study. The skeleton had appeared on the .'h'd day and the vm- 

 bryos were beginning lo assnnu' Ihe Pluleus-shape. In another culture 

 the skeleton began lo foini in Ihe course of the second day. .\l Ihe age 

 of 6 days the larva were found lo be well developed Plutei in the first 

 stage; in this stage they remained apparently unaltered for about 8 days 

 more; at the age of nearly two weeks the first indication of the postero- 

 dorsal arms appeared. At the age of three weeks Ihe stage shown in 

 PI. X, Fig. 2 was reached, and the fully formed larva shown in PI. X. Fig. 3 



