Chap. XI Mollusca, Radiata, and Acalephæ
I. Conchology.—General character of Ceylon shells 369
Confusion regarding them in scientific works and collections 369
Ancient export of shells from Ceylon 370
Special forms confined to particular localities 372
The pearl fishery of Aripo 373
Frequent suspensions of 374
Experiment to create beds of the pearl oyster 375
Process of diving for pearls 377
Danger from sharks 379
The transparent pearl oyster (Placuna placenta) 380
The “musical fish” at Ballicaloa 381
A similar phenomenon at other places 383
Faculty of uttering sounds in fishes 384
Instance in the Tritonia arborescens 385
Difficulty in forming a list of Ceylon shells 386
List of Ceylon shells 388
II. Radiata.—Star fish 395
Sea slugs 396
Parasitic worms 396
Planaria 398
III. Acalephæ, abundant 398
The Portuguese man-of-war 400
Red infusoria 400
Note on the Tritonia arborescens 401