298 SEALE. 



The nervous system Is similar to that of other members of this order, being 

 composed of the following three ganglia : ( 1 ) The cerebral ganglion may be seen 

 by folding back the labial palps; it is a large, pale, orange-colored mass halfway 

 between the base of the palps and base of the foot. (2) The pedal ganglion is on 

 the base of the foot in the middle on the dorsal side. (3) The parieto-splanchnic 

 ganglion will be found on the lower front curvature of the muscle closfe to the 

 extremity of the kidneys. The byssus and byssus gland are absent. 



DISTKIBUTION GIT THE PHILIPPINE WINDOW-SHELL. 



The ■window-shell is widely distributed throughout the Islands in 

 certain definite areas. A large bed exists in Manila Bay, especially in 

 the shallow arm of the bay east of Cavite known as Baeoor Bay. It is 

 also found at Paranaque; in fact, the entire east end of the bay from 

 Paranaque to Cavite is a potential bed for the window-shell. Kawit is 

 the center of activity for window-shell fishing for the Manila Bay beds. 

 Important beds also occur at Pangolao and Talibon in Bohol, at Valla- 

 dolid in Oriental Negros; in Capiz, Masbate, and Iloilo; in the Province 

 of Pangasinan, Luzon, and in numerous localities in Mindanao. Doubt- 

 less, there are a number of other places in the Islands where this shell is 

 found which have not been reported. Iloilo supplies large quantities of 

 shell for the Manila market. Shells from the Province of Pangasinan 

 seem to be uniformly thicker and more opaque than Iloilo shells, but 

 average slightly less in size, being 112 and 107 millimeters in diameter. 



In no place in the Philippines are these shells fished for the pearls 

 which they sometimes contain, but always for the shell alone. 



HABITS, CULTIVATION, AND FOOD OF THE WINDOW-SHELL MOLLTJSK. 



The window-shell mollusk is usually found in shallow water, but has 

 been known to exist in a depth up to 20 fathoms. It requires a bottom 

 of grayish or bluish mud where more or less fresh water is carried in b^' 

 streams. 



There is a large variety of marine life found in the Manila beds, 

 such as large quantities of clams and edible oysters; in fact, the cul- 

 tivation of the oyster and the window-shell is carried on simultaneously 

 by a number of fishermen. The oyster beds are staked oft by their re- 

 spective owners, and when fishing for window-shell or oysters outside of 

 their claims, all the small and half-grown window-shell oysters are col- 

 lected and planted on their oyster farms and kept there until they are 

 mature. The young shells can not be sold as they are not large enough 

 for windows. The adults keep the claim well supplied with spat. 



The owners of these claims club together and hire a watchman, who 

 is stationed in a house built over the water near the claims. 



The yield of the Cavite beds is estimated at 14,000 adult shells for a good 

 week's fishing. However, the fishing is intermittent, depending upon the demand 

 and also upon the owner's need of ready cash. The shells are fished entirely 

 at low tide in water of 1 meter or less in depth; the fishermen feel for them 



