The Hiftory c/ANIMALS. 
*5 6 
OJlrea conica fpinis ad or am undulatis . 
The conk OJlrea , with undulated/pines at the rim. 
This is about two inches in length, and an inch and a quarter in breadth at the larger 
extremity, from whence it gradually becomes fmaller to the other, at which the hinge is 
placed : the body of the fhell is rough and undulated, and has a few fhort fpines to¬ 
ward the edges, but rarely any about the middle j toward the rim, at the larger ex¬ 
tremity, there Hand three or four rows of long, robuft, and fharp-pointed fpines | 
they are not ftraight but undulated, or bent backwards and forwards, and make a 
kind of thick fringe, thole of the upper and lower valve meeting, and hiding the 
joining of the two parts of the fhell: the body of the fbell is of a dirty white, but 
the fpines are of an elegant purplifh-red, and make a very beautiful appearance. ’ 
It is frequent on the fhores of South America. 
Oflrea foliata imbricata albefcens. 
The whitijh , foliated\ and imbricated Oflrea. 
This is one of the molt extraordinary fhells of this genus j it’s figure is oval 5 it’s 
length about three inches and a half 5 it’s hinge is at the fmalleft end, and it’s*dia¬ 
meter at the other is two inches and a half: it is deeply finuated at the edge, and the 
furface is all over covered with tranfverfe, foliated protuberances, of an undulated 
form : they are flat, uneven, and notched at the edges, and there are ufually fix or 
feven feries of them placed at tolerably equal diffances one over another : the general 
colour of the fhell is white, but there are variegations of a bright rofe colour on it. 
It is a native both of the Eaft and Weft Indies, but is not frequent in the latter 
place. 
Oflrea hians globofa echinata . 
The echinated , globofe , gaping Oflrea . 
3Ci)e $et»sef)og= 0 |>ffer. 
This is a very lingular and pretty fpecies; it is about an inch in diameter, as much 
in length, and nearly as much in depth : the fhells are both gibbofe, or nearly he- 
mifpherical, and are fo fhaped, the upper one being fmaller than the under, that they 
never can clofe or fhut, but always leave a confiderable opening; the whole fhell is 
furrowed longitudinally, and is very thick-fet with fhort, crooked fpines, the points 
of them all turning toward the hinge : the colour is a tolerably clean white, without 
any variegation. 
It is frequent in the Eaft Indies, but rarely comes over perfedt. 
OJlrea dentata cra/Ta . ^ ^ ^ 
The thick , dentated Oflrea . SCfjt COCfcS'COUlb 
This is a thick and coarfe fpecies, but it has it’s Angularity, that may very well 
ftand in the place of beauty: it’s diameter in breadth is about four inches; it’s depth, 
from the hinge to the verge of the mouth, hardly three; it is elevated into three, 
four, or more very prominent and fharp ridges on the furface, with very deep, angu¬ 
lar furrows between them; thefe ridges are extended alfo at the verge, beyond the reft 
of the fhell, and form a deeply dentated edge: the colour on the outfide is a deep 
brown, with a tinge of violet; within it is of a pearly white : the furface is fome- 
what rough, with tranfverfe furrows j and the opening of the fhell, though fo deeply 
finuated, is formed fo nicely, that it clofes with great exadtnefs. 
It is a native of fome of the coafts of the Mediterranean : we have both this and the 
hammer-oyfter foffile in the fand-pits on Blackheath; and both, among many other 
fhells, in the ftone of which St Paul’s Church is built. 
The other fpecies of Oyfters are to be arranged under two or three divifions, and 
will then be eafily underftood by their fpecific names, without farther defcriptions. 
1. Of the more flat and fmooth kind, there are, 1. The common Oftrea. 2. The 
little, greenilh, oriental Oftrea. 3. The great, broad Oftrea, which produces the 
genuine pearl, and is thence called the Concha Margaritifera, and Pearl-fhell. 4. The 
great. 
