492 ON THE FAUNA AND BOTTOM-DEPOSITS NEAR THE 30-F.^r. LINE 



shells. The species was also present on Grounds III., VI., and VIII., 

 which are also fine sand, and scarce on XIV. and XIII., fine gravel 

 and coarse gravel with mud respectively. In Plymouth Sound it is 

 abundant on stony ground in 5 fathoms. 



Habits. A gregarious species (Bell), which can swim rapidly. It 

 does not appear to burrow like many other species of this genus. 



Distribution. Geographical. Mediterranean, Portugal, west coast of France, Channel 

 Islands, English Channel, Irish Sea (abundant), Clyde area, Shetlands (rare, Norman), 

 North Sea (once only, Pommcrania), Kattegat (chiefly on deep mud), Norway to Arctic 

 circle {vide Gourret, Bonnier, Bell, Walker, Hoyle, Norman, Metzger, Meinert). 



Depth. 3 fathoms (Walker) to 104 fathoms (Hoyle, No. 53). 



Bottom-dej)osit. In the Irish Sea Walker (Nos. Ill and 112) records it as abundant on 

 stony ground in 3-7 fathoms. Metzger (North Sea, No. 78), on sandy mud in 69 fathoms. 

 Pruvot (Mediterranean, No. 98) on sand, on gravel, and on mud. Marion (Mediterranean, 

 No. 74), on mud and on muddy sand in 34-50 fathoms. Meinert (Kattegat, No. 75), 

 generally on pure mud, occasionally on mud with sand or gravel, occasionally on clean 

 sand. In this case again the species is found upon deposits of very different texture. In 

 shallow water (3-10 fathoms) it appears to inhabit chiefly stony ground. 



Portunus pusillus (Chart XIII.) was most numerous on the Gravel 

 Grounds IX. and XI. to the west of the Eddystone. It was very rarely 

 obtained on the fine gravel ground XV., and on the fine sand grounds 

 IV., VI., and VII.. Occasional specimens were found on the Bolt 

 Head Shell Gravel and on the Prawle Stony Ground. The species was 

 never taken on the fine sand grounds 1., II., III., and V. 



On the whole, therefore, on the grounds under investigation, Portunus 

 pusillus lives principally on gravel, a few wandering on to the sand 

 grounds immediately adjoining the gravel. 



Distribution. Geographical. Mediterranean, Canary Isles, Portugal, Bay of Biscay, 

 English Channel, Irish Sea, Shetlands, Norway to Lat. 62°, Sweden, Kattegat, North Sea 

 (Milne-Edwards and Bouvier, Norman, No. 93, Gourret, Bonnier). 



Depth. Shore (rare. Bonnier, No. 10) to 98 fathoms (Milne-Edwards and Bouvier, 

 No. 80). 



Bottom-deposit. Milne-Edwards and Bouvier record Portumis pusillus from the Bay of 

 Biscay on nullipore ground, on fine sand, and on muddy sand. Metzger (No. 78), on stony 

 ground, on .sandy mud, on gravel, and on sand. Pruvot (No. 98) mentions it on sand 

 and gravel, and on gravel. Bonnier (No. 10), on muddy sand. Gourret (No. 31), on mud, on 

 gravel, and on muddy gravel, and Meinert (Kattegat, No. 75), generally on mud mixed 

 with gravel and stones, occasionally on tine sand. 



Corystes cassivelaunus (Chart XIII.) is found practically exclusively 

 upon clean fine sand, and is abundant on Grounds I. and III., or, 

 speaking more accurately, on the portions of those grounds which adjoin 

 each other. The hauls in which it was most plentiful are 91, 72, 57, 

 and 92, which it will be seen all lie near together. One specimen only 

 was taken on Ground II. (haul 22), and it was also met with on 

 Ground XVII. (Bolt Head Shell Gravel) in haul 27 only, probably 

 because this haul extended on to the fine sand. The species is 

 entirely absent from all the Eddystone Gravel Grounds. 



