M Y A. 
them is attended' with Confiderable difficulty. There are 
twenty-fix fpecies enumerated in Gmelin’s lad edition of 
Linnaeus’s Sydetn of Nature : 
1. Mya truncata s ihell ovate, truncate, and gaping 
greatly behind; tooth projecting forwards and very ob- 
tufe. It inhabits the European Seas; is two inches and 
a half long; the ffielT is of a dirty-white covered with a 
yellovvifh-brown ikin ; the inhabitant is frequently eaten, 
and is the principal food of fea-birds. It is defcribed and 
figured, as are leveral of the following fpecies, in Pennant’s 
Brit. Zool. yol. iv. 
2. Mya declivis: fhell brittle, femitranfparent; (loping 
downwards near the open end ; the hinge is (lightly pro¬ 
minent. Found about the Hebrides; the fifh. is in gene¬ 
ral eftimation among the inhabitants of thofe iflands. 
3. Mya arenaria : (hell ovate, rounded behind; tooth 
projecting forwards, rounded, and furnifhed with a lateral 
fmaller one. This fpecies is found in the European Seas,, 
under the fand ; is two inches and a half long, and of a 
yellowilh reddilh-brown. 
4.. Mya piftorum, or painter’s mya : (hell ovate : with a 
fingle, longitudinal, crenulate, tooth, in one hinge, and 
two in the other. There are feveral varieties of this fpe¬ 
cies, defcribed by different nnturalifts : lome of them are 
found in the frefh waters of this country, and other parts 
of Europe; fome in Barbary, and fome in Tranquebar. 
The (hell, which is nearly four inches long, and half as 
broad, is commonly uled to put water-colours in, whence 
we have its name ; it is covered with a brownifh or blackifli 
coat, under which it is yellowilh or green ; it is very thin 
and brittle, and does not gape at either end. 
It was,this fpecies, or one of its varieties, that M. Fau- 
jas St. Fond fuppofes to be the pearl-oyfter he met with 
in Scotland, during his travels in Great Britain fome years 
ago, and of which he has fince publilhed an account at Pa¬ 
ris. The following extrafts from his work contain fome 
faCts in natural hi (lory which we believe are little known : 
“ The mailer of the inn, who obligingly exerted him- 
felf refpefting every thing that could gratify my curiofity, 
brought me two (ilhermen whofe particular employment 
was (earthing for pearls. They conducted us to the river, 
wdiich runs in a very pure dream upon a bottom of fand 
or pebbles; and they loon brought up feveral dozens of 
(hells, from three and a half to four inches long, and a 
little more than two broad ; their exterior colour was a 
deep brown, inclining a little to green ; the upper (hell 
was thick, and of a line mother-of-pearl colour within, 
dightly tinged with rofe-colour. I regarded this fpecies 
as belonging to the Mya piCtorum of Linnaeus, or at lead 
as very nearly refembling it. The fidiermen, in confe- 
quence of a handfome reward which we promiled them, 
engaged to open thefe dtells in our prefence upon the 
bank ; but they dipulated for the refervation of the 
pearls, if any diould be found, that they might fell them 
to us at a feparate price s and to this proposition we ac¬ 
ceded. 
“ Imagining from this that we diould put a higher value 
on thole pearls which might be found while we were pre¬ 
fen t, thefe artful practitioners brought fome with them, 
which they dexteroufly introduced into feveral of the 
(hells in opening them : they appeared to be well prac- 
tifed in this petty fort of impofition, which however I 
detected in a manner that adonidied and perplexed them, 
and which deferves to be mentioned, as it depended upon 
a memorable faCt refpefting one of the caufes which con¬ 
tribute to the formation of pearl. I defired them to open 
the mufcles before my fellow-travellers, whild I went to 
amufe myfelf with (idling fome of them ; but they were to 
inform me when they difcovered any pearls. I was foon 
called, and Oiown a very fine pearl, perfectly round, and 
of a good colour. I looked at the (hell and the pearl, and 
then told them that the pearl was not found in the mufcle 
(hown to me. The ddiers allured me that it was, and ap¬ 
pealed to the tedimony of my companions, who confirmed 
their aflertion. I allured my friends, however, that they 
427 
were deceived-; and begged them to watch the filhers 
more narrowly the next time. I retired, a few deps, and 
in a minute or two, I heard one exclaim, We have found 
another. I went up; and, on examining the mufcle, 
pronounced that the pearl had for that time alfo been 
Hipped into the (hell. The pearl was beautiful; but the 
price they demanded for it was fix times its value. The 
filhers exhibited the ptmoft adonilhment; for, as I was at 
fome diitance from them, it was clear I could not have 
obferved their motions. My fellow-travellers, who at¬ 
tentively watched them, were themfelves deceived, or at 
mod entertained only a vague fufpicion; fo well (killed 
were thefe men in an art which procured them a few ad¬ 
ditional drillings from travellers. 
“ My art was fo fupernatural in their edimation, that 
they confeded the impofition, and frankly (howed us fome 
other pearls which they had in relerve for the fame pur- 
pofe. They were very anxious to learn my fecret, which 
would Cave them the pains of frequently opening a vad 
number of diells to no purpofe; for they feldom found 
above one or two pearls in a week. But, as they knew 
no other language than the Erfe, and not even fo much 
as a word of Englilh, I could explain myfelf only by figns 
and gedures ; and, though my indruCtions were not very 
difficult, I doubt whether they were completely intelligi¬ 
ble in a converfation of this fort. My fecret confided 
merely in examining attentively the outride of the muf¬ 
cles ; and, when neither of the parts had any cavity or per¬ 
foration, but prefented a furface fmooth and free from 
callodties, I could pronounce, without any apprehenfion 
of being deceived, that there was no pearl in (rich a (hell. 
If, on the contrary, the (hell was pierced with auger- 
worms, and indented by other worms of the fame kind, 
there were always found pearls more or lefs valuable, or, 
at lead, the embryos of pearls. This obfervation, which 
I have found invariably true hitherto, was the refult of 
fome enquiries, in which I had been engaged a long time 
before, refpefting the formation of that beautiful animal 
produft. Buffon introduces the information, which I 
communicated to him upon this fubjeft, in his article 
upon pearls, in vol. iv. of the Natural Hidory of Minerals. 
At that time I had difcovered that the pearl-fifli is at¬ 
tacked by two claifes of enemies. One is a very fmail 
auger-worm, which penetrates into the infide, near the 
edge of the valve, by working a longitudinal paffage be¬ 
tween the different laminae that compofe the cover. This 
(mail channel, on extending to an inch or an inch and a 
half in length, doubles back in a line parallel to the fird, 
and is feparated from it by a very thin partition of (helly 
matter. Thefe two parallel lines difcover the direftion 
of the worm in entering and returning, which is alfo dif- 
tinguidiable on the furface by two (mall holes, clofe to the 
edge, and in general near the mouth of the (hell. The 
parallelifm of the two padages may be demondrated by 
introducing a pin into each orifice. At the inner ex¬ 
tremity, however, there is a (mail circular portion, formed 
by the worm in turning round. As thefe (mail channels 
or covert-ways are excavated in the part neared the mo¬ 
ther-of-pearl, ordlvery internal coat, the pearly juice foon 
extravafates, and produces protuberances, in that direc¬ 
tion. The cylindrical bodies thus formed, may be con- 
bdered as elongated pearls, adhering to the internal lining 
of the (hell. When feveral worms of this kind penetrate 
near each other, and unite their labours, the refult is a 
fort of pearly wen, with irregular protuberances, in which 
the ilfues of the padages which they have formed are ea- 
fily didinguithable. Another lea-worm, much larger, and 
of the family of the multivalvous (hell-nfh, attacks the 
pearl-diells in a much more ingenious manner. This 
worm is a Pholas, of the fpecies of daftylus. I have in my 
cabinet an oyder from the coad of Guinea pierced by one 
of thefe pholades, which are (till as they were found in the 
heel of the _oyder._ The (hells of thele dngular pholades 
are hinged in the form of a crooked bill : the fmail holes 
which they bore are in the figure of a pear; and pearls of 
this 
