COPEPODS OP THE WOODS HOLE REGION" 7 



out ; of course, it holds good continuously with reference to the sand 

 obtained from offshore banks and during dredging operations. 



The sand can be washed conveniently in two long-handled dippers ; 

 with one dipper enough sand is scraped from the bottom to fill it 

 one-quarter full, the other three-quarters being filled with water. 

 The water is then poured back and forth between the two dippers, 

 thoroughly roiling the sand. The sand grains sink quickly to the 

 bottom each time, while the copepods are forced out by the currents 

 and remain in the water above the sand. Finally, with a pause 

 long enough to allow the sand to settle, the wash water is poured 

 into a pail or other convenient receptacle. When a sufficient quan- 

 tity has been thus obtained it can be strained through an ordinary 

 townet. 



By this means it has been ascertained that the sand has a rich 

 and varied fauna of its own, even more sharply distinguished from 

 the pelagic and littoral faunas than they are from each other. Of 

 course, a few littoral species get in the wash water, but the number 

 is surprisingly small and nearly always they can be recognized by 

 their size alone, the sand copepods being usually less than half a 

 millimeter in length. Furthermore these sand dwellers are thus far 

 all harpactids with the exception of the genus Gyclopina^ one of the 

 Cj^clopoida. Many of the harpactids described by Scott and Sars 

 are probably true sand dwellers, although they could not be 

 definitely recognized as such owing to the manner in which they were 

 captured. Sars, in his Crustacea of Norway (vol. 5, p. 398), men- 

 tioned " many interesting copepods obtained from an off-shore bank 

 with a coarse sandy bottom at a depth of 30 to 40 fathoms." As this 

 is the typical form of the sand dwellers, and as all his species were 

 considerably less than a millimeter in length, it is probable that some 

 of them at least habitually lived in the sand. In his account of the 

 copepods of the Scottish Antarctic expedition,^ T. Scott mentioned 

 15 or 20 species of harpactids as " obtained from siftings of dredged 

 material " near the South Orkney Islands. Thompson and A. Scott, 

 in enumerating the copepods collected at Ceylon,^ reported many 

 of the harpactids as " found in pearl oyster washings " and " in the 

 general washings of invertebrates." Some if not most of these must 

 have been sand-dwelling copepods. 



As a sample of what may be obtained from washing the sand it 

 may be said that a single 10-quart pailful of wash water from the 

 sand of the shore of Katama Bay, Marthas Vineyard, yielded 800 

 of these sand dwellers, distributed among 25 different species. Only 

 3 of the species and less than 50 of the specimens could be classed 

 as littoral forms; the others may be designated as benthonic. 



2 Trans. Roy. Soc. Edinburgh, vol. 48, pp. 521-599, 1912. 



* Report on the pearl-oyster fisheries of Ceylon, Suppl. Rep. No. 7, pp. 227-307, 1903. 



