Arctic and North- Atlantic Starfishes. 403 
Originally my intention was only to settle whether one or 
several year-classes of a species of starfishes occur at a 
locality, and, if several, whether one of these is more nume- 
rously represented than the others. In the course of my 
investigations it appeared that a similar number of annual 
classes is gathered at the same locality of more than one 
species. In Pontaster tenuispinus we find an annual class 
with a dise-radius of 3-4 mm., another of 8-10 mm. We 
find the same number of Ctenodiscus ecrispatus, Psilaster 
andromeda, etc., or else the numbers are very close to those 
mentioned for Pontaster tenutspinus. Therefore, if we could 
determine the age of a year-class for one species, that of the 
others would also be known. Among some echinoderms 
from Utne, Hardanger, I was fortunate enough to find some 
very small Psilaster andromeda, which had apparently been 
recently transformed to the bottom stage. ‘his was conse- 
quently group 0, other material belonged to group L., ete. 
The measurements mentioned in this paper are given in 
the table on p. 402, the remainder appear in ‘ Nogen aste- 
riders alder og aarsklasser.” 
I shall first endeavour to show that starfishes occurring at 
a locality are, as a rule, represented by several year-classes, 
but only one of them numerously. ‘The ‘ Voeringen’ took 
153 Pontaster tenuispinus off the mouth of the Sogne Fjord: 
of these one specimen had a dise-radius of 3 mm., the rest 
measured 5-12 mm., with a maximum of 119 specimens (or 
76°8 per cent. of the total number) at 8-10 mm. A year- 
class is evidently gathered about these measurements. The 
3 mm. specimen belongs to another year-class, as is clearly 
shown by 384 specimens taken by the ‘ Voeringen’ off the 
Fro Islands; of these one specimen had a disc-radius of 
9mm., the rest 1-5 mm., including 12 specimens at 3 mm. 
The conditions in the two localities were therefore quite 
different : off the Fro Islands there was a maximum of 12 
specimens at 3 mm. and one only at 9mm.; the Sogne Fjord 
locality had, on the contrary, a maximum of 48 specimens at 
9 mm., but one only at 3 mm. Common to both localities is 
the circumstance that two year-classes were represented, only 
one of them numerously. 
At a station off the coast of Romsdal the ‘ Voeringen’ took 
52 Pontaster tenuispinus, which had a disc-radius of 6-11 mm., 
with a maximum of 45 specimens at 7-9 mm. Evidently 
only one annual class was represented here, and that one 
must have been of the same age as the large group from the 
station off the Sogne Fjord. As stated above, there was at 
