SCYPHOMEDUSAE 



359 



In the layer of 500-600 m. there are as many or more specimens of the same size than 

 in the stratum of 1500 m. ; moreover, his largest specimens are not caught at the greatest 

 depths (600 and iioo m.). 



Table IV 



Showing the bathymetrical distribution of the three stages in pigmentation represented in the 

 specimens obtained by the 'Michael Sars' in the North Atlantic (see Broch's fig. 2, p. 6) 



Broch's table on Periphylla regina on p. 9 is more convincing. The specimens of 10 

 and 14 mm. diameter live at a depth of 900 m., those at 1250 m. are 15I and 37 mm. in 

 diameter, at 1500 m. 34, 35, 40 and 43 mm. and one specimen at 4500 m. measured 

 55 mm. in diameter. Broch's material, however, is too scanty for any conclusions to be 

 drawn in this respect. 



With regard to the rich material recorded by Broch from the Sognefjord (p. 8) his 

 list has not been worked out sufficiently to be of any use. The few data given in that 

 table are not at all in favour of his statements, because large and small individuals occur 

 side by side in several layers (75, 500 and 750 m.). 



Our Table III shows, as does table 2 of Broch, that the small dodecabostrycha and 

 hyacinthina are absent from the deeper strata, that the larger regina is absent from the 

 upper layers and that in intermediate strata forms of all sizes are represented. As the 

 small dodecabostrycha lives in the upper layers and the large regi?ia is found in the 

 deeper horizons it is true that the size increases with the depth, but in a sense different 

 to that stated by Broch, who took our three developmental stages as three different 

 species. This has been discussed at length under bathymetrical range. As shown there 

 the regina stages during their growth sink slowly into deeper layers. 



Broch asserts further that there is an increase of the number of individuals according 

 to increase in depth. I cannot agree with him in this respect. It is a pity that the 

 abundant Sognefjord material of about 1000 individuals has not been worked out as 

 carefully as the Atlantic specimens. 



Let us examine Broch's table 3. According to his assertion the largest number ought 

 to be found at the greatest depth. This is, however, by no means the case. At his 



