•404 Dr. J. A. Grieg oti the Age of some 



this locality a maximum at 8-10 mm., while at the station 

 off the coast of Roiiisdal it was at 7-9 mm. Tlie difference 

 must be attributed to the fact that there were better conditions 

 of life at the one locality than at the other. 



Quite the same result that the Fro Islands material gives 

 is exhibited by 55 specimens from a locality in the Kiira Sea. 

 As the table shows there is a marked maximum of 49 speci- 

 mens at 3-5 mm., while only 5 specimens have a disc-radius 

 of 7-10 mm. From another locality in the Kara Sea there 

 are 37 specimens, which show that three year-classes may be 

 represented at a locality, but only one of them numerously. 

 We have first a large group of 29 specimens which have a 

 disc-radius of 2-7 mm., with a maximum of 22 specimens at 

 3—5 mm. Then, a group of 7 specimens with a di.sc-radius 

 of 9-13 mm., and, finally, one specimen of 23 mm. Each of 

 these groups must represent an annual class, the youngest of 

 which only was numerous. 



The material of Pontaster tei^uispinus examined by me 

 shows that this species has a year-class at 3-4 mm., another 

 at 8-10 mm., and 1 have had some specimens with a disc- 

 radins of more than 13 ram. The material of this last group 

 is unfortunately so sparing that it has not been possible to 

 determine where its maximum is to be found; I should be 

 inclined to think that it must be looked for at about a radius 

 of 15 mm. With a disc-radius of 23 mm. Pontaster tenui- 

 spiiius has attained its maximum of growth. Whether it is 

 possible to find one or two year-classes between 13 mm. and 

 23 mm. cannot at present be definitely determined, but I am 

 most inclined to think that representatives of two year-classes 

 are to be found between these two sizes. 



From three localities in the Barent's Sea I have measured 

 169, 149, and 335 specimens respectively of Ctenodiscus 

 crispatus. The specimens from the first locality measured 

 3-13 mm. and had a maximum of 128 specimens (or 77*7 per 

 cent, of the total number) at 7-10 mm. ; at the second locality 

 there was a maximum of 132 specimens (or 88*6 per cent.) at 

 8-11 mm. — these specimens measured 6-13 mm. ; at thetiiird 

 locality the specimens measured 6-16 mm. — at 9-12 mm. 

 there was a maximum of 267 specimens (or 79*7 per cent, of 

 the total number). If we compare the material, we find that 

 the majority of the specimens at all three localities are of the 

 same size and represent the same annual class. It is very 

 probable, however, that at two of the localities, at least, there 

 were specimens of still another year-class, for material from 

 other localities indicates that the'smallest specimens from the 



