139 
rearing the Ophiurid from the larvæ, on the other hånd, proved 
successful. 
Larvæ in all stages of metamorphosis occurred in great num- 
bers. On picking out from the plankton such larvæ, as were in 
the more advanced stages of metamorphosis and placing them in 
separate dishes, I had the joy of seeing them go on metamorphos- 
ing normally, and almost any number of young Ophiurids could be 
obtained. The question was now how to arrange for suitable con- 
ditions for these young Ophiurids, so that they would feed and grow 
to the desired size. Some mud from the locality, where the grown 
Amphiura’s abound, was sifted through fine silkgaze in order to 
avoid all larger organisms, and especially to avoid the presence in 
it of young Ophiurids the origin of which was not controlled. I put 
some of this sifted mud in some flat dishes, adding some Nitschia- 
culture, and the young Ophiurids were placed in the dishes. They 
at once buried themselves in the mud, and in the course of a 
few days it was evident that they had grown in size and a new 
arm joint was about to form. Before leaving the station I put a 
number of such young Ophiurids, reared from Ophiopluteas manens, 
into an aquarium with sifted mud and Nitschia culture added. Dr. 
Ostergren kindly promised to take care of them and, at my 
request, after about four months sifted the mud and sent me what 
was left of the culture, preserved in aleohol. Examining this mate- 
rial I found that, while some of the young Ophiurids had hardly 
grown at all, others had grown not inconsiderably having 4 joints 
in the arms, not counting the terminal joint. 
On comparing the young Ophiurids thus reared with young 
specimens found on sifting the mud from the Ampliiura- locality, 
the youngest of which had only 3 — 4 joints in the arms, it was 
evident that it was really the young Amphiura that had been 
reared in this way. It is true, the reared specimens had not grown 
so far as to develop the two infradental papillæ, which represent 
the most prominent A nip hi ura- character. But among those spec¬ 
imens collected from the mud from the Amphiura -locality every 
transitional stage was found from young specimens not yet having 
the infradental papillæ developed to such as had the Amphiura- 
characters distinetly developed; and there was the most perfeet 
conformity between the specimens reared in the aquaria and the 
