130 TAGE SKOGSBERG 



This writer's investigations with regard to Macrocypridina, Homarus and Carcinus gave 

 the following results: 



Marrocijpndia. GypHdina ( M acrocypHdina) castanea G. S. Brady. 



Only five specimens were recorded; they measured 6,0, 4,0, 1,9, 1,8, and 1,8 mm. 



,, Apparently three stages, I., II., and IV., were represented in the five specimens; with 

 a growth-factor of 1,5, the lengths 1,8, 2,7 (missing), 4,0, and 6,0 are related as in the other 

 species" (p. 279). 

 HoiiKinis. ' Hotnarus americanus MiLNE Edwards. 



This investigation is based on the statements as to length given by F. H. Herrick in 

 the work of 1896 quoted above. The result of this study quite coincides on the whole with 

 the result previously obtained by F. H. HerrICK, cf. p. 125 above. It is noteworthy, 

 however, that G. H. FowLER pointed out that there must be a difference between the 

 early, larval moults and the moults at a more advanced age, p. 280: ,,If a lobster con- 

 tinued to moult at the same brief intervals, and to grow by the same increment as 

 did Herrick 's larvae, it would be 10^4 inches long at the end of its first year (instead of 

 2-3 inches), and in five years would be a dangerous monster of portentous size." 



Carcinus. Carcinus maenas Leach. 



G. H. Fowler based this investigation on measurements of the greatest breadth of the 

 carapaces that were thrown off by eleven individuals kept in aquariums; the measure- 

 ments were previously published by H. C. WILLIAMSON, 1903. „The observed breadths 

 seemed... to fall into groups round obscure medians." Although the average values for 

 these classes of breadths seem to be anything but certain, they agree in quite an 

 amazing way with BrOOKS's law. In the following table the left row represents ,,the 

 means of these vaguely indicated groups", the right row ,,the successive products, by an 

 empirically - found growth - factor, of means starting from 4,80, the lowest observed mean 

 of the series" (p. 281). 



4,80 4,80 X 1,27 =■ 6.09 



6,05 6,09 X 1,27 = 7,73 



7,75 7,73 X 1,27 =- 9,81 



9,61 9,81 X 1,27 = 12,45 



12,65 j 12,45 X 1,27 = 15,81 



16,02 15,81 X 1,23 = 19,44 



19,50 19,44 X 1,23 = 23,91 



23,89 23,91 X 1,23 = 29,40 



29,30 \ 29,40 



As will be seen from the above table G. H. Fowler was of the opinion that in this case 

 too a smaller growth-factor could be observed for older stages. For more details see this author's 

 accoimt, pp. 280, 281, 



