70 
East Indian form, not to the second form referred to by Pal la s, 
that from the Belgian coast. 
The priority rule has, indeed, done harm enough in a number 
of cases, where change of names could not be avoided. It is not 
unreasonable to ask that at least no change of old generally used 
names should be made without the most careful consideration of 
all the questions connected with each case. 
13. Antedon petasus (Dub. & Kor.). 
(Fig. 6, a—h.). 
The observations on the embryology of this species recorded 
in the author’s paper „Notes on the development and the larval 
forms of some Scandinavian Echinoderms“ x ) have revealed the faet 
that quite noteworthy differences exist between Antedon petasus 
and the allied species A. adriatica, mediterranea and bifida in 
regard to their development. Thus, while in the three latter spec¬ 
ies the eggs remain attached to the pinnules until the embryo is 
hatched as a fully formed larva with its ciliated bands etc., in A. 
petasus the eggs * 2 ) are free, probably pelagic and the embryo is 
hatched before the appearance of the ciliated bands. Also in the 
embryological processes, especially as regards the enterocoel ves- 
icles and the entoderm, very remarkable differences appear to exist 
between the said species. 
These facts naturally lead to the question, whether then A. 
petasus can really belong to the same genus as the other species 
named; the question was hinted at in the paper quoted, but the 
discussion thereof was left for the present occasion. 
In the revision of the genus Antedon s. str. given recently by 
A. H. Clark 3 ) the species referred to the genus are divided in 
two groups, one, comprising A. mediterranea Lmk. and adriatica 
A. H. Clark, being characterized by the long, approximately uni- 
') Vid. Medd. Vol. 71. 1920. p. 150. 
2 ) I regret having omitted to State in the paper quoted that the eggs of A. 
petasus show most distinetly the same peculiar structure of the follicular 
membrane as is found in Ant. mediterranea. (Comp. Ludwig. Die Bil- 
dung der Eihiille bei Antedon rosaceus. Zool. Anzeiger. III. 1880. p.470). 
3 ) Beitråge zur Kenntniss d. Meeresfauna Westafrikas, herausgeg. v. W. 
Michaelsen. Hamburg. Lief. 2. 1914. Echinoderma II. Crinoidea. p.313-318. 
