FAUNA OF THE CLYDE SEA-AKEA. 



465 



is the shallowest, being about 23 fathoms. lu the case o£ some 

 of the other basins, however, it is so far from marking out their 

 limits that it does not touch the tops of the ridges which sepa- 

 rate them. To Dr. Murray I owe the suggestion that it might 

 be worth while to compare the faunas of the deepest parts of 

 the basins, taking some other contour-line as the upper limit. 

 I have therefore gone over the Table given above and selected 

 from it those species which are found in proximity to the bottom 

 of each basin. The depressions themselves vary so much in 

 depth that I have thought it advisable to record both the forms 

 which are found below the 50-fathom [line and (in a sej^arate 

 column) those which are found w .hin, say, 5 to 20 fathoms 

 of the bottom of each basin. Furthermore I have excluded 

 those free-swimming forms whose distribution in regard to depth 

 cannot be regarded as absolutely fixed. On this ground I have 

 omitted the Fishes, Cephalopoda, Amphipoda, and part of the 

 Macrurous Crustacea (viz. the genera Sippoli/te, Pandalus, and 

 their allies) ; the Polyzoa, Hydroida, and Sponges have also been 

 neglected because they have been insufiiciently studied. 



In the subjoined Table the following symbols have been 

 used : — 



* = occurring at the depth mentioned in the head of the 

 column. 



t = occurring in the locality, but at a depth less than those 

 under consideration in the table. 

 "W' = Widely-spread species. 

 N = Northern species. 

 S = Southern species. 



