JCjver since I published my report: »On tlie development 

 of Echinocyamus pusilhis (O. F. Muller)-;^ my attention has 

 been almost incessantly devoted to tlie development of other 

 forms of echinoderms, and specially to that of Echinus mili- 

 aris L. which is very common on the west coast of Sweden. 

 As early as 1893 I had succeeded in rearing great quantities 

 of larvse of this species trough all the developmental stages 

 up to the small sea-urchins which crawled abont on the bottom 

 of the aqnaria. Every succeeding summer I have repeated 

 these rearing experiments at our marine biological station, 

 Kristineberg, and always with the same happy results. 



Having, however, been entirely occupied in pressing busi- 

 ness at our State-Museum during the greatest part of the 

 period which has elapsed since the date mentioned, I have 

 not yet been able to finish my researches and to order them 

 so satisfactorily, that I should like to see them published. 

 A great number of illustra tive figures are already drawn, it 

 is true, together with a series of sections across the plnteus 

 with the outgrowing sea-urchin in different developmental 

 stages, which have been arranged in five double plates in 

 quarto, comprising 180 figures — but notwithstanding this, 

 it has seemed to me desirable to delay the publication of 

 any of my results until some rather obvious lacnnee had 

 been filled. 



But having just received a most interesting paper on 

 »The development of Echinus esculentus» by MacBride, where 

 he treats the same qnestions which have formed the subject 

 of my own investigations, and being uncertain when I shall 

 be able to complete my studies on the matter, it may be appro- 

 priate to publish the following preliminary notes. The reader 



' Royal Society of sciences of Upsala. 



