FISHERY RESOURCES OF THE PHILIPPINE ISLANDS. 30] 



are the great top shell {Trochus niloticus Linn.), the green snail {Turbo 

 marmoratus Linn.), and the chambered nautilus {NautiliLs pompilius 

 Linn.). 



THE OKEAT TOP SHELL. 



The great top shell {Trochus niloticus Linn.) (Plate XI, figs. 1 to 

 4) known locally as the lock, conic shell, trochus, susong-dalaga, or 

 minong, is a large, conical, top-shaped shell, found in abundance in many 

 islands of the Philippine Archipelago. Aside from the true pearl oyster, 

 this shell is the one in greatest demand for manufacturing buttons. As 

 a matter of fact, owing to its cheapness, it is frequently made into 

 buttons in preference to employing the pearl oyster. The great top shell 

 when mature is from 10 to 15 centimeters in diameter and a trifle less 

 in height ; it has many close whorls, the largest of which flares decidedly. 

 The shell is marked with radiating or zigzag bands of red, violet, or 

 brown; the aperture is oblique and has a spiral operculum. An adult 

 shell 10 centimeters in diameter weights 330 grams. 



The great top shell is usually found at low tide near the outer edge 

 of coral reefs or under large rocks, and while small quantities may be 

 encountered on almost any coral reef in the Archipelago, they are espe- 

 cially abundant in the vicinity of Sitanki, along the coast of Pangasinan, 

 and Ambos Camarines, Luzon, and on the northern coast of Palawan, 

 the eastern coast of Samar, and in the vicinity of Masbate. There are 

 also numerous places on the coasts of Mindoro where they are abundant. 

 I noticed a number of these shells washed up on the beach on the 

 eastern side of, the Gulf of Davao. 



The soft portion of the great top shell is regarded by the Filipinos 

 as a very fine article of food and, as a matter of fact, this species of 

 mollusk is more sought after for its meat than for its shell. One proof 

 of this is in the numerous piles of empty shells to be found on the 

 beach in localities near the ocean. It is usually noticed that they have 

 been placed on the fire, in order to cook the animal, after which it is 

 easily removed from the shell. Of course, shells treated in this man- 

 ner are spoiled so far as their" commercial value is concerned. The proper 

 way to remove the animal is to place the shell in hot water, as the shell 

 is in no wise injured liy this treatment. 



So far as my experience shows, the great top shell is always more 

 or less solitarj' and while five or six are frequently found under one large 

 stone they never occur in beds or in great numbers over a given limited 

 area. 



The average annual export of this shell from the Philippines during the 

 past four years has been about 350,000 kilograms valued at about 60,000 

 pesos. The price fiuctuates greatly. For a considerable period the stand- 

 ard price was 7.50 pesos per picul for middle grade shells. The Manila 



