63 



a manner in some of the Aviculce proper. The orbicular species are re- 

 markable also for their very elaborately scaled or foliated structure, those 

 that are least winged being generally the most scaled ; and the colours are 

 in some few kinds as brilliant as can well be imagined. Both varieties of 

 Avicula produce pearls, but it is to the large round A. margaritifera of the 

 tropical and subtropical seas in both hemispheres that we are indebted for 

 the pearls of commerce. The choicest pearls are formed within the fleshy 

 part of the mantle, owing to some disorganization of the secreting gland 

 which causes the pearly nacre, used for the lining of the shell, to accu- 

 mulate in little pea-like balls ; and great is the eagerness with which they 

 have been procured in all ages for ornamenting the person.* 



The Avicula are abundant in the tropical and subtropical seas, and are 

 handsomely, but with rarity, represented on our own shores by the A. Ta- 

 rentina, whose home is in the Mediterranean. The smaller species, some 

 of which are extremely fragile, attach themselves chiefly to bunches of 

 zoophytes. 



1. serata, Reeve. 



2. ala-corvi, Chemn. 



3. ala-perdicis, Reeve. 



4. Anomioides, id. 



5. aquatilis, id. 



6. argentea, id. 



7. assula, id. 



8. Atlantica, Lam. 



9. barbata, Reeve. 



10. castanea, id. 



11. cetra, id. 



12. Charnoides, id. 



13. cornea, id. 



14. crocea, Chemn. 



Species. 



15. Cumingii, Reeve. 



16. electrina, id. 



17. exiniia, id. 



18. fibrosa, id. 



19. fimbriata, id. 



20. flabellum, id. 



21. flammata, id. 



22. flexuosa, id. 



23. formosa, id. 



24. fucata, Gould. 



25. gregata, Reeve. 



26. heteroptera, Lam. 



27. hystrix, Reeve. 



28. imbricata, id. 



29. inquinata, Reeve. 



30. iridescens, id. 



31. irradians, id. 



32. irrasa, id. 



33. lacunata, id. 



34. lata, Gray. 



35. lentiginosa, Reeve. 



36. libella, id. 



37- lotorium, Lam. 



38. macroptera, id. 



39. Malleoides, Reeve. 



40. marmorata, id. 



41. maura, id. 



42. muricata, id. 



* " During the continuance of the pearl-fishery, there is no spectacle which Ceylon affords 

 more striking to the European than the Bay of Condeatchy. ' This desert and barren spot is at 

 that time,' says an eye-witness, ' converted into a scene which exceeds in novelty and variety al- 

 most anything I ever witnessed. Several thousands of people, of different colours, countries, 

 castes, and occupations, continually passing and repassing in a busy crowd ; the vast numbers 

 of small tents and huts erected on the. shore, with the bazaar or market-place before each ; the 

 multitude of boats returning in the afternoon from the pearl-banks, some of them laden with 

 riches ; the anxious expecting countenances of the boat-owners, while the boats are approaching 

 the shore, and the eagerness and avidity with which they run to them when arrived, in hopes of 

 a rich cargo ; the vast numbers of jewellers, brokers, merchants, of all colours and all descrip- 

 tions, both natives and foreigners, who are occupied in some way or other with the pearls, some 

 separating and assorting them, others weighing and ascertaining their number and value, while 

 others are hawking them about, or drilling aud boring them for future use ; — all these circum- 

 stances tend to impress the mind with the value and importance of that object which can of 

 itself create this scene.' " — Johnston, Introcl., p. 53. 



