178 



NOTES on the DISTKIBUTION of AMPHIPODA— 



The proportion of species to genera in small and large 

 areas ; also of species at various depths. 



By Alfbed 0. Walkee, F.L.S. 



[Read March 13th, 1896.] 



The remarks of Prof. Herdman in his Presidential 

 Address to Section D (Zoology) at the meeting of the 

 British Association last September (1) as to the relative 

 proportion of genera and species in large and small areas, 

 and (2) on Dr. Murray's theory that the number of 

 species of marine animals is greater, per haul, at and 

 near the 100 fath. line than in depths less than 50 fath., 

 have led me to make some investigations into the 

 distribution of the Amphipodous Crustacea in our district 

 as compared with Norway. 



I have chosen the Amphipoda in preference to any 

 other order of Crustacea because those of Norway have 

 recently been described by Prof. G. 0. Sars in the first 

 part of his magnificent work on the Crustacea of Norway, 

 and also because more than half of the species of 

 Malacostraca in our district belong to it. 



The proportions of genera to species have already been 

 given by Dr. Herdman in the Ninth Keport of the 

 L.M.B.C. (1896), and I will only repeat the summary : 



Bhos Bay, 1 to 10 fath., species are to genera as 

 115:100. 



L.M.B.C. District, shore to 70 fath., species are to 

 genera as 159 : 100. 



Norway, shore to 1215 fath., species are to genera as 

 232:100. 



