4*1 8 ; 
43 
Liquid a- 
l>out the 
oyder feen 
with the mi- 
crofcope. 
f e mi aur ei- 
ta. 
Jiriata . 
fornicate. 
JinenJu, 
CONCHOLOGY. 
Chap. IV. 
vatlons a very pleaiing entertainment. In the clear li- 
quor many little round living animalcules have been 
found, whole bodies being conjoined, form fpherical 
.figures, with tails, not changing their place otherwife 
than by finking to the bottom, as being heavier than 
the fluid ; thefe have been feen frequently feparating, 
and then coming together again. In other oyfters, 
animalcules of the fame kind were found, not conjoin- 
ed, but fwimming by one another, whence they feern- 
ed in a more perfect fiate, and were judged by Mr 
Leeuwenhoek to be the animalcules in the roe or femen 
of the oyfter. 
A female cyder being opened, incredible multitudes 
of fmall embryo oyders were feen, covered with little 
fhells, perfectly tranfparent, and fwimming along dow- 
ly in the liquor ; and in another female, the young 
ones were found of a browner colour, and without any 
appearance of life or motion. 
Monfieur Joblot alfo kept the water running from 
oyderg three days, and it appeared full of young ey- 
fters fwimming about nimbly in it ; thefe increased in 
fize daily ; but a mixture of wine, or the vapour of vi- 
negar, killed them. 
In the month of Augud oyders are fuppofed to 
breed, becaufe young ones are then found in them. 
Mr Leeuwenhoek, on the 4th of Augud, opened an 
oyder, and took out of it a prodigious number of 
minute oyders, all alive, and fwimming nimbly about in 
the liquor, by means of certain exceeding fmall organs, 
extending a little way beyond their diells ; and thefe he 
calls their beards. In thefe little oyders, he could dif- 
cover the joinings of the diells ; and perceived that there 
were fome dead ones, with their diells gaping. Thefe, 
though fo extremely minute, are feen to be as like the 
large oyders in form as one egg is to another. 
As to the fize of them, he computes, that 120 of 
them in a row would extend an inch ; and confe- 
quently, that a globular body, whofe diameter is an 
inch, would, if they were alfo round, be equal to 
1,728,000 of them. He reckons 3000 or 4000 are 
in one oyder, and found many of the embryo oyders 
among the beards ; fome fadened thereto by flender 
filaments, and others lying loofe : he likewife found 
animalcules in the liquor 500 times lefs than the em- 
bryo-oyders. 
It is not uncommon to fee on oyfier-ihells, when in 
a dark place, a fhining matter or bluilh light, which 
dicks to the fingers when touched, and continues Alin- 
ing and giving light for a confiderable time, though 
without any fenfible heat. This fhining matter being 
examined with a microfcope, is faid to confid of three 
forts of animalcules 5 but it is more probable that it is 
the phofphorefcent light which feparates from animal 
matters, particularly fifh, in the incipient dage of the 
putrefactive procefs. 
109. O. oval, fiightly eared, fmooth, with an ob- 
lique bafe ; !•§• inch long, ji broad. Mediterra- 
nean. 
* xio. O. oval, with longitudinal, irregular, undula- 
ted filiform ridges •, infide fmooth, gloffy white, with 
a pearly hue. European feas, fliores of Britain. 
1 1 1 . O. rough, oblong, linear, with divergent hinges; 
internally vaulted. Red lea. 
XI 2. 0 \ rough, lamellated, unequal, and glabrous 
within ; lower valve large;' 4 inches long, Chinefe 
diores. 
1 13. O. equivalve, pellucid, flattened, oval, with fpondyloi- 
perpendicular, undulated Arise on the upper valve : dea. 
3 inches long, broad. India. 
1 1 4. O. plaited, and terminating in a long, incurved, forjkahlii^ 
hollow beak ; middle ribs with imbricated, fpinous 
wrinkles’; 2 inches long, and 1 broad. Red flea. 
1 15. O. with longitudinal, wrinkled plaits; lower plicatula. 
valve fmaller and datter ; varies much in diape and 
dze. American and Mediterranean feas. 
1 16. O. oblong, rugged; upper valve lamellated, rojlrata. 
with a denticulated margin ; the lower excavated, and 
longitudinally grooved. Pvlediterranean. 
117. O. nearly equivalve, thick, rough, lamellous ; viriginica. 
one valve with a prominent beak ; 9 inches long, and 
4 broad. American and Indian oceans. 
1 1 8. O. upper valve flat, lower one hollow and dri- cornucopia: 
ated ; rough with fcales, wrinkles and plaits, and ter- 
minating in an elongated beak. Indian and African 
oceans. 
119. O. thin; lower valve convex and thicker; th eparajilica, 
other flat. Atlantic and Indian feas. — This fpecies, 
like the common oyder, Axes itfelf to the roots and 
branches of trees, particularly the mangrove, which 
grow out of the water. It varies in form and dze, 
and is often as large as the palm of the hand. 
120. O. thin; upper valve longer and more con -exa/bida. 
vex. Adriatic. — It is found fixed to other (hells. 
1 21. O. rugged, with imbricated lamellae ; margin crifiata. 
with obtufely plaited teeth ; 1 inch long. 
122. O. equivalve, roundifh, fmooth, fiat ; li'nOa&f.fencgalen- 
diameter. Shores of Senegal. Jis. 
123. O. thin, deprefled, rough, unequal; upper Jlellata. 
valve ribbed ; ribs with a few fpines. Guinea. 
124. O. oval, thin, terminating in a fhort, acute, ovalis. 
lateral channelled beak ; Arise perpendicular, unequal, 
obfolete ; 1 inch long. 
125. O. roundiih, fnowy, thin pellucid; upper papyracea. 
valve terminating in a fhort, acute beak. 
126. O. equivalve, orbicular, white, with concentric annulate. 
femicircles. North feas. 
127. O. equivalve, oblong, white, glabrous, Aria -retufa. 
ted ; with an umbo or knot remote from the hinge. 
North feas. 
C. Hinge with a perpendicular grooved line. 
128. O. equivalve, obovate, unequal, rounder at perna. 
one end ; 7 .\ inches long ; has fome refemblance to a 
gammon of bacon. Indian and American feas. 
129. O. equivalve, with a larger lobe, forming aifogonum , 
right angle with the hinge ; from 5 to 7 inches long, 
and i-^ broad in the middle ; fhell blackifh, violet 
without, pearly within. Indian ocean and South feas. 
Is a rare fhell. 
130. O. equivalve, orbicular, compreffed, membra- epliippium, 
naeeous ; 5 inches long, 5-J- broad. Indian ocean and 
Cape of Good Hope. Very rare. 
131. O. equivalve, thin, pellucid, and pointed at pidla, 
the liinge ; the other end dilated ; margin acute ; 2 
inches long, more than an inch broad. Red fta. 
132. O. flat, hoary, thin, pellucid, lamellated; in -legumen^ 
terdiees of the grooves black ; 2 inches long, 4 lines 
broad. Nicobar iflands. 
133, Q. 
