THE CEYLON PEARL-OYSTER. 295 
I then tried the Colombo Museum in the hope of getting some 
oysters with pearls cm situ, but Dr. Pearson had no preserved 
material to spare. I tried to obtain material from Madras from 
Mr. Hornell, but he wrote me, in January 1911, that his own 
material was exhausted, and that he would not be able to obtain 
any more till the next inspection, a year later. However, 
H.H. the Jam Saheb of Nawanagar most kindly sent me some 
preserved specimens of this species with pearls in situ from the 
Gulf of Kutch, and I hope, in a later publication, to be able to 
put forward some observations on the actual process of pearl- 
production, based on these. 
The followi ing material was available for these investiga- 
tions :— 
(i.) Twenty-one pearls bought in Ceylon. It is, of course, 
possible, though not probable, that some of these originally came 
from elsewhere, e.g. the Persian Gulf vid Bombay, but they, or 
at least the great majority of them, were certainly derived 
from J/. vulgaris, the pearls of which have a characteristic 
colour and lustre quite different from that of the pearls found in 
M. margaritifera and M. maxima. 
They were small ‘“ fine pearls,” mostly spherical, a few oval or 
slightly lenticular. One wasa brown pearl formed in the mantle- 
margin from the prismatic substance. They were all decalcified 
and examined whole, cleared in oil of cloves, and drawn. They 
were then sectioned (except in the case of three examples which 
were preserved whole). Their nuclei were in no cases Cestodes ; 
they usually contained a cavity with a few granules surrounded 
by spheerocr ystal-like matter, allied to or identical with the 
“ repair-substances ” described below. In several cases, however, 
the actual nucleus was a grain of sand. These specimens are 
preserved as preparations XL, XLII, XLII, XLIV, XLV, 
SCV DI a GEV) LEV a LAY Be: GeV, p, 
biVon Gi ae LiVee;. LEV a; LIV 1, LEV s,.and LIV « 
(Pls. XLI.-XLITI. figs. 35-45 and Pls. XLV., XLVI. figs. 50-57). 
(ii.) Dr. Kelaart’s Material in the British Museum. 
In 1901, when I was investigating the origin of pearls in 
Mytilus, Mr. E. A. Smith, 1.8.0., allowed me to examine five old 
specimens of the Ceylon Pearl-Oyster from Dr. Kelaart’s 
collections in the British Museum. Mr. Smith very kindly 
allowed me to make further use of some of this material for the 
present investigations. 
The specimens are labelled :— 
“1 specimen of pearls in ovaria, 
3 specimens of pearls in mantle, 
1 specimen of ova of Entozoa in liver of J/eleagrina 
margaritifera.” 
The specimen with‘ pearls in ovaria” was a pearl-oyster with 
[87 
