NO. 5 BARNARD: AMPHIPODA 27 



"1 I I I \ I I I I i 1 1 1 \ — I — I — I r 





I I I I I I ! I I I \ 1 L_J ! i \ L 



1 2 3 4 5 S 7 S 9 10 II 12 IF 14 IS 16 IT 18 19 ZO 



Depth in Hundreds of Meters 



Graph 12. Extremes of known depth distribution of amphipod 

 species collected in the submarine canyons and basins. Each bar 

 represents a species or a group of species having similar depth 

 ranges. In depths greater than 100 ra the ranges are classed to the 

 nearest 100 m. Shallower than 100 m the species are grouped in 

 classes of and 40 m. For instance, the first bar shows four species 

 having depth ranges limited to 0-40 m. Bar 3 shows 12 species 

 having ranges of 0-200 m. Bar 16 shows three species having depth 

 ranges between 40 and 200 m. 



On the bars near the top of the graph are dots representing the 

 depths at which the species have their highest densities. Bar 6 shows 

 8 dots, each representing the highest density for each of the 8 species 

 having that depth range. On bars 1-5 most of the species have their 

 densest populations in 0-10 m and a single dot represents those 

 species. Thus, in bar 2, with 9 species, only 2 have their highest 

 densities in depths exceeding 10 m. Insufficient data are available 

 for species below bar 14. 



25 of the 185 known shelf species are associated with subtidal algae. 

 These amphipods may be carried into the heads of canyons only in asso- 

 ciation with detached algae. 



Comparison of the Faunal Composition of Canyons and Basins 

 With That of the World Bathyal Zone 



Although bathyal depths have been defined as exceeding 200 m 

 (Hedgpeth, 1957), I have used in the following treatment the depth of 



