252 CEYLON MARINK BIOLOGICAL REPORTS. 



The shoal is clearly visible in line and clear weather ^ as the white nature of the sandy bottom 

 niftki's tlie Avater a light green. At such times the fallen beacon sliows up as a dark sliadoAv, as do 

 several tanks sunk on the same spot. Karativu tope and beacon can just be seen, which, together with 

 Kutrimalle tower and Kellar obelisk, form good marks to locate the position. 



The sunken beacon mentioned above has been recently examined with a view to raising it, but it 

 was found in a veiy bad condition. Such a beacon, with an iron tray between the legs at the base and 

 hea^^ly ballasted with a lumdred tons or more of stone ballast, might perhaps stand the monsoon, but 

 the position is very exposed, and the sand veiy coarse and loose. A station buoy meets all present 

 requirements, and is removed at the end of the fishing season. 



Aripu JReef lies due west of Aripu tope, at a distance of 4 miles, and occurs on the edge of the 

 inshore overfalls of a shallow water plateau of from 2 to 3 fathoms, which extends out from the shore, 

 and starting at Kutrimalle Point sweeps gradually in a curve to the north-west, and finally west-nortli- 

 west. The coral reefs commence off Silavatarai, and are named Silavatarai, Aiipu, and Vankah reefs. 

 Silavatarai reef forms the southern extremity. These coral reefs, which extend in a north-westerly 

 direction for a distance of 5 miles, cover an area of about 4 square miles, and terminate on the west in 

 from 4 to 5 fathoms of water. On the north a deep arm of the sea rmis in towards Vankah, and divides 

 Aripu from Vankali reef. 



The area on the inshore side of Aripu reef lias been examined Arith a view to finding a suitable 

 area protected by the reef, for another uurseiy like the one imder the lee of the Silavatarai reef, where 

 unfortimately there is only 12 feet of water ; but although deep water was found on the northern extremity 

 of the Aripu reef, it is not protected sufficiently. 



The reef is made up of three groups of coral, including the Silavatarai patch, which dry at low 

 water. Madrepore predominates, and occurs in great variety. On this reef the sea breaks in places, 

 which is accounted for by shallow water, there being a depth of under 6 feet in parts. 



Vankali Reef lays off the port of that name and north of the deep arm of the sea mentioned as 

 dividing this from the Aripu reef. It occurs on the edge of the overfall of the shallow inshore plateau, 

 which here extends in a more westerly direction, and is at the northern extremity, 9 miles from the shore. 

 Tlie plateau inside is shallow, i.e., 2 to 2| fathoms. The coral grows in dense sohd masses on the 

 overfalls, and terminates on the west face in from 5 to 6 fathoms. The most massive growths occur in 

 from 1 to 2 fathoms. The reef covers an area roughly of 6 square miles, and is 6 miles long. It terminates 

 north, where the shallow plateau ends, and soundings deepen to 5 fathoms. 



The characteristic of the coral growth here is Turhinaria cincerens in huge masses, rising abruptly, 

 and growing in separate dense growths with deep chasms between, which make walking over the reef (of 

 which an extensive area dries at low water) a dangerous busmess, imless one is attended by a boat and 

 companions, for one might get badly hurt by a sudden fall into the deep abysses, and as the coral overlaps, 

 it would be an easy matter to fuid oneself fast under the overhanging edge. On this reef, as on the Bar 

 reef, the sea does not break, due to the fact that the coral grows out into deep water. 



An iron beacon has recently been erected on this reef, which has been placed on the highest and 

 densest part of the reef, and in a position where it is hoped it will stand. The structure is of railway iron, 

 and is surmounted by a black baU 6 feet in diameter over an inverted triangle, which can be clearly seen 

 8 mUes. A beacon on this reef was necessary, as the only bearing available on the northern paars is Aripu 

 tope, and a second landmark was much needed. 



4. — Beacons and other LAiJDMARKS. 



Since the Company took up the lease of the pearl banks considerable additions have been made 

 to the landmarks, in order to facihtate the location of the various paars and rocky areas. The positions 

 of the conspicuous natural landmarks have been fixed, and the positions of the original marks verified 

 and corrected where necessary. 



The beacons which the Company have erected are Kutrimalle, Karativu, and Dutch Bay 

 beacons ; and of late the two on the Bar reef, one on the Vankali reef, and another on Aripu reef. 



