THE WINDOW-PANE OYSTERS. 45 



comparatively simple matter to stake out rough enclosures, which 

 could then be thickly stocked \yith the window-pane oysters. 



Uppu-aru or Uppar. 



This backwater is deeper than the Sambore, upwards of a fathom 

 in most parts, so that genuine diving is required. Before diving, 

 and while the divers were under water, the boatmen beat the sides 

 of the boat to scare away sharks and crocodiles should any be in the 

 vicinity. 



The beds, such as they are, occur on the Kiniyai side of the wide 

 bay into which the Uppu-aru expands at its mouth. On the opposite 

 side, bordering upon the " Oopah estate " the current is too strong. 



Just inside the bay, round the point of the ferry, two bivalve chippi 

 were picked up looking quite normal, but they proved to be dead. 

 It was indeed the common saying that the " muttu chippi " of the 

 Uppu-aru were all dead. Nevertheless, on the north side, which is 

 flanked by a bank of mangroves, whose lower line of foliage was flush 

 with the surface of the water, some living placunae were found. A 

 sample of half a dozen ranged from 5| by 5 inches to 7 by 6 inches. 

 I returned all except one, which harboured the same Copepod gill 

 parasites that I found in the Sambore river, but failed to find in the 

 Tamblegam chippi, although I searched carefully for them.* 



Proceeding along towards the head of the bay some healthy looking 

 specimens of medium size were procured, but they also were dead ? 

 then approaching a kallam in one fathom more dead valves were 

 found. Striking off towards the centre a diver picked up a pale 

 grajdsh gelatinous sea-haref [Aplysiidoe) studded with bright emerald 

 green areolae and with retractile pinnate tassels all over the body ; 

 they called it " kadalnatthu " (sea-foam). Nearer the shore we took 

 three more dead bivalves. 



At the head of the bight between two creeks, among dead rem- 

 nants, one living placuna of medium size (5| by 5 inches) was taken, 

 the shell shomng the marks of a fish bite. In the mid-bay, opposite 

 to the sea-opening, only dead valves were found. 



Parasitic Larv^. 



It is still uncertain how the primary infection of the liver with the 

 flatworm larvae, which are believed to be identical with the pearl- 

 inducing parasites, takes place, whether they are passively ingested 

 with the food or actively migrate from the outside. However this 

 may be, it stands to the credit of Mr. Hornell to have shown for the 

 first time how secondary infection may occur, namely, by the endo- 

 genous formation of a new generation of larvse within a parent cyst. 



* Since found (October). f Perhaps Acclesia cirri/era. 



