262 DR. H. LISTER JAMESON ON 



to Mr. E. Hopkins, of Hatton Garden, for specimens of Ceylon 

 Pearls ; to Professor W. A. Herclman, F.R.S., for specimens of 

 Pearl-Ojsters from Ceylon, and for allowing me to examine his 

 preparations ; to Mr. Max Mayer, of Hatton Garden, for specimens 

 of pearls for my work ; to H.H. the Jam Saheb of Nawanagar, 

 for specimens of Pearl-Oysters from the Gulf of Kutch ; to Prof. 

 L. G. Seurat, for pearls from New Caledonia, Madagascar, and the 

 Gambier Archipelago ; to Mr. A. E. Shipley, F.R.S., for allowing 

 me to examine and make use of his specimens of Tylocephala and 

 allied genera of Cestodesfrom Ceylon fishes ; to Mr. E. A. Smith, 

 I.S.O., for permitting me to make use of material in the British 

 Museum (Natural History) , including specimens from Dr. Kelaart's 

 collection ; and to Mr. A. Van IVoorden (of the firm M. Myers, 

 Mother-of- Pearl Merchants) for specimens of Lingah and other 

 shells. 



After this paper was handed in I received a copy of Rubbel's 

 paper (34 a) setting forth in greater detail the results already 

 published by him (33 and 34). Herr Rubbel and 1 have arrived, 

 working independently on widely different molluscs, at identical 

 conclusions on several important points, such as the nature of 

 Herdman's " calcospherules." Where practicable, I have inter- 

 polated references to his work in the text, and my only regret is 

 that it is not possible to discuss his valuable work more fully in 

 the present paper and to dwell at length on the many points where, 

 adopting a slightly different terminology and interpretation of the 

 phenomena, our respective works lead to the same conclusions. 



(2) Outline of the recent Investigations in Ceylon. 



In January 1902 Professor W. A. Herdmanwent to Ceylon, at 

 the request of the Colonial Office (who availed themselves of his 

 services on the recominendations of the Council of the Royal 

 Society and of Professor Ray Lankester), to investigate the 

 condition of the Pearl-Banks. Professor Herdman took with him 

 as his assistant Mr. James Hornell, who remained in Ceylon to 

 carry on the work after the former's return to England in April 

 of the same year, and who collaborated in the preparation of 

 Professor Herdman's reports. Professor Herdman's visit in 1902 

 gave him seventy-eight days in Ceylon, and was largely spent in 

 an extensive biological and faunistic survey of the pearl-banks, 

 carried out on two successive dredging-cruises, each of several 

 weeks' duration ; and he credits Mr. Hornell with the major part 

 of the observations on Pearl-production (Royal Institution 

 Lecture of March 27th, 1903) (14). Prof. Herdman himself 

 always seems to have regarded the condition and welfare of the 

 natiuul beds of oysters as a more important problem than the 

 question of pearl-production (Report on the Ceylon Pearl 

 Fisheries, Part I. p. 5, and Part V. p. 29 ; also Report of the 

 Annual Meeting of the Ceylon Company of Pearl Fishers, Ltd., 



