28 



The Cliank-beds. — These fall Into two categories [a) 

 fine sands admixed with a certain amount of mud and 

 known as /'/;-«/5 (^^(nj"sv) * in contradistinction to pars, the 

 rocky banks where pearl oysters live, and [b] chankiL 

 7iilani or chank places — sands more or less mixed with 

 dead madrepore branches {challi) and other par detritus 

 adjacent to the margins of the pars or pearl banks. Up 

 to the present neither survey nor tabulation of these 

 chank'beds has been made — an investigation shortly to 

 be undertaken. The principal are of course known and 

 their positions have been shown tentatively in the sketch 

 plans which accompany my Report to the Government 

 of Madras on the Indian Pearl Fisheries in the Gulf of 

 Mannar, (Government Press, Madras, 1905) but no 

 detailed work has been attempted, and the boundaries 

 given are certain to be largely amended when we have 

 more exact knowledge. We have yet to learn the 

 relative fishing value of the different beds and are 

 ignorant how far these are stable or variable from year to 

 year. 



The principal food of the chank consists of various 

 tubicolous polychait worms, chiefly small Terebellids, 

 Eunicids and the like. A piral indeed connotes the 

 presence of vast multitudes of these worms ; it may be 

 defined as a stretch of fine sand probably with a definite 

 admixture of mud, supporting a profuse polychcet fauna 

 living in arenaceous tubes, on which the chanks prey. 

 This constitutes a characteristic chank-polychict forma- 

 tion widely spread between the 8 and 10 fathom lines off 

 the Tinnevelly coast. It is noteworthy that m and around 

 the pearl banks on the opposite Ceylon coast few chank- 

 beds are found and chanks are not numerous except in 

 a few restricted areas. In this connection w^e have to 

 note that the Ceylon sands on the Pearl P^ishery coast 

 between the 5 and 10 fathom lines consist of coarser sand 

 grains than those of the Tinnevelly shallow water plateau 

 and, unlike the latter, are generally very clean and almost 

 free from admixture with mud. 



The principal piral ground lying off Tuticorin is 

 sub-divided into a number of separate pirals actually 



* This luimu iippcais to l)c' very iincient in uii^in ; its deiivati'iTi is unknown 

 and the word does not appear in a,ny Tamil dictionary I have consulted. 



