622 DEPTHS OF THE OCEAN 



depth, as shown by the graph (Fig. 474). We see, for 

 instance, that in the southern section, if we want to get 

 individuals of an average size of 30 mm., we must fish 250 

 metres farther down than we would in the northern section. 



The vertical distribution of Cyclothone signata is very 

 different from that of C. microdot. We have captured many 

 individuals at a depth of 300 metres, at any rate, in our southern 

 section. The bulk, however, were found at a depth of 500 

 metres. In the hauls made at greater depths, the quantity 

 diminished so rapidly that we may assume that a large portion 

 of the fishes were caught during the process of hauling 

 in, and that there is only a comparatively thin layer below 500 

 metres in which they live. In a vertical haul from a depth of 

 4500 metres to 1500 metres we caught no individuals of this 

 species, but, on the other hand, we secured three individuals 

 in a haul from 1350 metres to 450 metres. 



Cyclothone signata is, accordingly, found in an intermediate 



layer with a maximum in the number of individuals at about 



500 metres. In the case of this species, too, we note that the 



younger individuals are mainly to be found high up in the water 



(notice particularly the southern stations), and that the same 



size is to be found deeper in the southern section than in the 



northern (see Figs. 473 and 474). 



Vertical We have a remarkable parallel to the vertical distribution 



distribution of q{ these two species of fish in the case of the species of 



'y"-- j.g^ prawns. These latter, along with the black fishes, form 



a populous and characteristic "community." We have come 



across no fewer than about forty species of pelagic prawns, of 



which we shall here refer only to Aca^tthephyra inu/tispina and 



A. purpurea. 



Acanthephyra nuiltispina shared with Cyclothone niicrodon 

 the peculiarity that the largest and oldest individuals were found 

 in the nets towed at the greatest depths, say, at 1000- 1500 

 metres (see Fig. 475). At depths between 500 and 750 

 metres we met with medium-sized specimens, and in the upper 

 layers, from 50 to 150 metres, we found the larvae. These 

 larvae were taken in quantities, whereas formerly only a single 

 individual collected by the Prince of Monaco, described by 

 Coutiere as Hoplocaricyphus similis, but now identified as a larva 

 of Acanthephyra multispma, was known. 



Acanthephyra purpurea resembles Cyclothone signata, in 

 that its' distribution is chiefly confined to an intermediate 

 layer between 500 and 750 metres in depth. Our appliances 



