Arctic and North- Atlantic Starjiahes. 403 



Originally my inlontion 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 a|)peared that a similar number of annual 

 classes is gathered at the same locality of more than one 

 species. In J^onta^ter ttnuispintis we find an annual class 

 with a disc-radius of 3-4 mtn., another of 8-10 mm. We 

 find the same number of Ctenodiscus cn's/atus, Psilaster 

 audiomeda, etc., or else the nutnhcrs are very close to those 

 mentioned tor Fontaster tenuispt'nus. Tlierefore, if we could 

 determine the age of a year-elass for one species, that of the 

 others would also he known. Among some ecliinoderms 

 from Utnc, Hardanger, 1 was foitiinate enough to find some 

 very small Psilaster andromeda, which had apparently been 

 recently transformed to the bottom stage. This was conse- 

 quently group 0, other material belonged to group I., etc. 



The measurements mentioned in this paper are given iu 

 the table on p. 402, the remainder appear in " Nogen agte- 

 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 

 l.OS Pontaster tenuispinus off the mouth of the Sogne Fjord: 

 of these one sj)ecinien had a di.>c-radiu8 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 34 specimens taken by the * Voeringen ' off the 

 Fro Islands ; of these one specimen had a disc-radius of 

 1) mm., 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 mn). and one only at 9 mm.; 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 tiiat two year-classes were represented, only 

 one of them numerously. 



At a station off the coast of Romsdal the ' Voeringen' took 

 52 Pontaster tenuispinua, 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 



