40 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 125 
Atlantic. It might be mentioned, however, that species of this genus 
occur on the South Atlantic coasts of South America (S. marplatensis 
and S. sphaeromiformis) and Africa (S. hartipes). 
The remaining eight isopod genera are divided evenly between the 
two coasts. The east coast genera are: Accalathura, Carpias, Cymodo- 
cella, and Skuphonura. The following four genera are represented on 
the Pacific coast but not on the Atlantic: Gnorimosphaeroma, Iani- 
ropsis, Jaeropsis, and Janiralata. Although absent from the Atlantic 
coast, Janiropsis and Jaeropsis are represented elsewhere in the 
North Atlantic (Wolff, 1962). Janiropsis breviremis occurs in the 
northeastern Atlantic (British Isles, Denmark, western Norway). As 
for Jaeropsis, one species (J. brevicornis brevicornis) occurs on the 
northwest coast of France and on the Channel Islands, and another 
(J. rathbunae) is found in Bermuda. 
Six of the seven isopod families and both tanaidacean families 
represented in the buoy collections occur on both the Atlantic and 
Pacific coasts. The one exception, the monogeneric family Jaeropsidae, 
is absent from the Atlantic coast, but, as previously mentioned, it is 
represented by a species in Bermuda and by another on the Atlantic 
coast of Europe; hence, the continent is no barrier to distribution, 
at least of the isopod and tanaidacean families in the present study. 
As indicated above, the continental barrier is progressively more 
effective for lower taxonomic categories—about 50 percent at the 
generic level and about 80 percent at the specific level. 
