THE CEYLON PEARL-OYSTER, 339 
a quadruple pearl, showed nuclei transitional between these two 
types. 
There remain the eight examples which had to be sectioned 
to disclose the nature of their centres, owing to opaqueness. ‘The 
first, Preparation XCIII, had a dark pseudo-nucleus which 
proved to be composed of stratified amorphous substance, in fact, 
a sort of horny pearl or periostracum-pearl. It was too hard 
to section properly, and its real nature was discovered only 
by dissection of the pseudo-nucleus. Preparation XCIV was 
a triple pearl, and contained pseudo-nuclei of three kinds, a 
* Kelaart” pseudo-nucleus, one composed of columnar substance, 
and one composed of concentrically stratified amorphous substance 
Preparation XCV had an irregular dark nucleus which in section 
proved also to consist of stratified repair-substance, interstratified 
with granules. In Preparation XCVI the centre was a hard 
mass a columnar substance, coutaining a body that broke away 
and may have been either amorphous substance or a hard body of 
foreign origin. Preparation XCVITI contained a typical columnar 
body, masked by a thick outer coat of amorphous substance. 
The remaining three had pseudo-nuclei of ordinary columnar 
substance. 
I cannot say whether any of the above pearls contained 
minute quartz-grains or other foreign inorganic bodies, as 
this cannot be determined, even with the aid of polarised light, 
in a great many eases, until sections are cut, owing to the high 
degree of double refraction possessed by the conchyolin, and the 
distortion of its original arrangement in the decalcifying process. 
But such foreign bodies were detected in two pearls given to me 
at the same time by Mr. Mayer, which were, however, more 
probably from Margaritifera margaritifera var. mazatlanica 
(Panama Shell) than from J/. vulgaris. 
F. Collection of Ceylon Pearls given to me by 
Mr. EB. Hopkins. 
In October last Mr. E. Hopkins, dealer in precious stones, of 
Hatton Garden, kindly gave me a parcel of fifteen small pearls, 
which he believed to be Ceylon Pearls. He wrote me (letter of 
26th October, 1911): “The pearls were obtained from a dealer 
whose son visited the Ceylon Fisheries on the last occasion when 
they were open, and from what he has told me I have every 
reason to believe that these were part of the goods which he 
brought back.” These fifteen pearls were decalcified and examined 
as transparent objects, and four of them, which could not- be 
satisfactorily made out otherwise, were subsequently sectioned, 
Most of these pearls were of the « muscle- pearl” class, small and 
angular, but two or perhaps three, both from their more spherical 
shape and different nuclei or pseudo-nuclei, may more properly be 
treated as parenchyma-pear!s. 
Twelve of these pearls had centres of the kind characteristic of 
29* 
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