Notes on the development and the larval forms 
of some Scandinavian Echinoderms. 
By 
Dr. Th. Mortensen. 
(With 8 text-figures.) 
CONTENTS. 
Introduction. 
I. Ophiura affinis Ltk. (?). 
II. Amphiura filiformis (O. F. Muller). 
III. Brissopsis ly rifer a (Forbes). 
IV. Stichaster rosens (O. F. Muller) (?). 
V. Antedon petasus (Duben & Koren). 
VI. On the nervous system of Echinoderm larvæ. 
During a stay at the Swedish Zoological Station at Kristineberg, 
Fiskebåckskil, in August-September 1918 I had the opportunity of 
making some observations on the development of some of the Echi¬ 
noderms occurring there. A renewed visit to the said station from 
the end of July till the middle of September this year (1919) enabled 
me to continue these researches. My aim being to acquire a ful¬ 
ler knowledge of the development of the Scandinavian Echinoderms, 
and especially of the different larval forms, it will need continued 
researches, which will evidently require visits to different places 
on the Scandinavian coasts and thus occupy a rather long time. 
I have therefore deemed it reasonable to publish this preliminary 
notice of the results hitherto acquired. 
I beg to tender my sincere thanks to the authorities of the 
Swedish Zoological Station, Kristineberg: Professor Hj. Thée 1 and 
Dr. Hj. Ostergren for the cordial hospitality offered me and for 
their untiring efforts in satisfying my — I fear rather trouble- 
some — needs of material for my researches. 
The results were obtained partly by direct rearing of the larvæ 
in question, partly through combinations of known facts, e. g. the 
