338 DK. H. LYSTER JAMESON ON 



Three of these pearls were decalcified, and one of them, Preparation 

 LXXXYI A, was also sectioned. All showed centres of the same 

 class as those of the pearls in Dr. Kelaart's collection — that is to 

 say, central cavities containing irregular conchyolin-like strands 

 and a few grannies. Two of these pearls were fair spherical 

 pearls, about 3 mm. in diameter, which would have ranked as 

 " tine " pearls or " cyst-pearls," but for blemished surfaces. The 

 third was a multiple pearl, secondarily attached to the shell, and 

 showed, by the presence of distinct traces of hypostracum in its 

 substance, that it had arisen in a muscular part. 



E. Collection of Pearls given to me hy Mr. Max Mayer. 



In April 1911, Mr. Max Mayer, of Hatton Garden, London, 

 and Paris, dealei- in precious stones, most generously gave 

 me for the purposes of my work a number of pearls, mostly 

 of the baroque and seed class (though some could better be de- 

 scribed as pearls that ^Yould have ranked as small " fine "' pearls, 

 but for defects of shape, colour, or surface). These included 

 a sample which, after eliminating a number of pearls that, 

 from their colour and other qualities, Mr. Mayer considered 

 were derived respectively from Australia and Panama (these will 

 be dealt with in another paper), left a mixed lot of 115 pearls, 

 most of which showed more or less of the characteristic and 

 indescribable creamy colour which is distinctive of the pearls 

 of Margarltifera vulyaris. Mr. Mayer had no hesitation in 

 saying that the majority of these were almost certainly Ceylon 

 pearls, though he emphasized the fact that it is not often that 

 pearls reach the European markets accompanied by " certificates 

 of birth," and that the sources of these specimens could only be 

 judged from their respective characters. 



These 115 pearls were decalcified and eight of them were 

 sectioned, and several others were dissected to expose the 

 nature of the " nucleus " or pseudo-nucleus. 



Of this collection not one had a nucleus that could be identified 

 as a Cestode, or indeed as any parasitic worm. Sixtj^ of them had 

 sphasrocrystal-like pseudo-nuclei composed of columnar repair- 

 substance, sometimes simple, sometimes stratified, sometimes 

 interstratified with other repair-substances. In some cases a few 

 granules could be detected in the centre, in others nothing of the 

 kind could be made out. These pseudo-nuclei were generally less 

 transparent than the residue of the pearl, often almost opaque 

 but in every case their nature was obvious. Forty-two pearls 

 were of the kind described from Dr. Kelaart's specimens in the 

 British Museum, /. e. they had either no obvious nuclei or their 

 centres contained cavities in which were a few strands of 

 conchyolin-like substance. Six others were of the same class, but 

 contained some i-efractive granular matter. One double pearl 

 showed a columnar pseudo-nucleus in one constituent and a 

 centre of the " Kelaart " type in the other, while another, 



