THE CEYLON PEARL-OYSTER. 339 



a quadi'uple peail, showed nuclei transitional between these two 

 types. 



There remain the eight examples wliich had to be sectioned 

 to disclose the nature of their centres, owing to opaqueness- The 

 first, Pre^^aration XCIII, had a. dark pseudo-nucleus which 

 proved to be composed of stratified amorphous sul)stance, in fact, 

 a sort of horny pearl or periostracum-pearl. It was too hard 

 to section properly, and its real nature was discovei-ed only 

 by dissection of the pseudo-nucleus. Preparation XCIV was 

 a triple pearl, and contained pseudo-nuclei of thiee 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 

 pi'oved also to consist of stratitied repair-subi^tance, interstratified 

 with granules. In Preparation XCVI the centre was a hard 

 mass of columnar substance, containing a body that broke away 

 and may have been either amorphous substance or a hai'd body of 

 foreign origin. Pi'eparation XCVII contained a typical columnar 

 body, masked by a thick outer coat of amorphous substance. 

 The remaining three had pseudo-nuclei of ordinaiy 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 cases, until sections are cut, owing to the high 

 degree of double i-efraction possessed by the conch yolin, 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, wliich were, however-, more 

 probably from Margaritifera margaritifera var. mazailanica, 

 (Panama Shell) than from J/, vidgaris. 



F. CoUectioti of Ceylon. Pearls given to me hy 

 Mr. E. Hopkins. 



In October last Mi-. E. Hopkins, dealer in ])i'ecious stones, of 

 Hatton Garden, kindly gave me a parcel of fifteen small pearls, 

 which he believed to be Ceylon Peai-Js. He wrote me (letter of 

 2Gth October, 1911): " Tiie 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 eveiy 

 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, wex-e 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 ditterent nuclei or pseudo-nuclei, may more properly be 

 treated as parenchyma-pearls. 



Twelve of these pearls had centres of the kind characteristic of 



22* 



