28 AXEL OHLIN, ARCTIC CRUSTACEA. 



obtained by the »Helgoland» Expedition »in der Nansenrinne» 

 in lat. SV 20' N., long. 19 E., and another one by »Olga» 

 between South Spitzbergen and Hope Island. Besides the 

 stations enumerated above, where it was dredged during the 

 last three Swedish Arctic Expeditions, tliese are, as far as 

 I have been able to find in the literature, the only certain 

 localities hitherto recorded of its distribution. Stuxberg states 

 that it does not occur E. of the Kära Sea, and the linds of it off 

 Kamtschatka and in the Bering Straits are already shown 

 to have arisen from some confusion with Crangon salebrosus 



OWEN. 



It is worth while remarking its singular distribution in 

 the Spitzbergian and Greenlandian Seas. It has not as yet 

 been obtained on the West Spitzbergen, but it seems to be 

 rather abundant farther east, in the Barents and Kära Seas. ; 

 while in these seas, Sclerocrangon boreas, which is so abun- 

 dant off West Spitzbergen. becomes rather searee here. The 

 same we might state with regard to East G-reenland. Although 

 BucHHOLZ says that Sclerocrangon hore.as »gehört daselbst 

 ebenfalls zu den sehr häufig vorkomnienden Formen», it must 

 be pointed out that, during the Swedish Expeditions of 1899 

 and 1900, this species was only dredged at one station, and 

 was represented by a single specimen, while Sclerocrangon 

 ferox was obtained at no less than seven stations in several 

 specimens. Moreover, Sclerocrangon boreas is by far, next 

 to Hippohjte polaris, perhaps the most common decapod on 

 both sides off Baffin Bay, as Hansen and I myself can testify; 

 while the other species, as mentioned above, have been hitherto 

 obtained in those seas only at four stations and in a small 

 number of individuals. 



T hus it seems as if they do not like living together, 

 but substitute each other. It has often been remarked that 

 Sclerocrangon boreas lives in more shallow water, while 

 Sclerocrangon ferox is an inhabitant of the deep-sea, and that 

 theory may partly hold good. Nevertheless, it does not fally 

 explain its singular distribution; for, in the shallow seas E. 

 of Spitzbergen, Sclerocrangon ferox is very common, and, on 

 the other hand, Sclerocrangon boreas has been taken at a 

 depth of 200 fathoms. 



I think, therefore, that we must look for the explanation 

 in the temperature of the water. As a rule the bottom 



