The Hiflory o/’ ANIMALS. 199 
and narrow perforations quite through the body of the {hell. While living, the crea¬ 
ture is fomifhed with a great number of very fine fpines, like fegments of briftles $ 
but thefe fall off very eafily, fo that we rarely fee any of them. 
It is a native of the American Seas $ we have it frequent in our cabinets. 
Centronia deprejfa biperforata margine digit at 0. 
The flat■ biperforate Centronia 3 with a digitated edge . 
This might, at firft fight, be efteemed only an accidental variety of the preceding 
fpecies, but the difpofition and form of the rays on the fummit {hew that it is truly a 
diftindt fpecies: it’s figure approaches to round, but it is fomewhat irregular; it’s dia¬ 
meter is two inches and a half, and it’s thicknefs, including both the {hells and the 
hollow for the habitation of the animal, is not more than a fifth of an inch 5 part of 
the verge is even and undivided, but part is deeply and irregularly finuated, and forms 
about ten digitations: on the oppofite or undivided part of the fhell there are two per¬ 
forations ; they are about a third of an inch in length, and half their length in dia¬ 
meter : the digitations in this, and the other fpecies which have them, feem formed 
of thefe perforations, continued to the edge of the (hell: in the center of this fpecies 
there are five narrow, long, and fharp-pointed rays, formed of double feries of lines, 
pun&ated as in the others 5 there are alfo fome annular lines at fmall diftances, running 
all over the furface j and, when the creature is living, there are many feries of fine, 
{lender fpines. 
We have it from the fhores of the American iflands. 
Centronia ovata deprejfa margine undulato fexies perforata. 
The oval , deprejfed Centronia, with an undulated edge , and fix per¬ 
forations. 
This is another of the flat kinds; it is about two inches in length, and an 
inch and half in breadth at the larger end ; it is confiderably fmaller at the other, but 
is obtufe at both, and is not more than a fifth of an inch in thicknefs : the whole 
verge is undulated, but is not digitated in any part, and toward the verge there {land, 
at pretty regular diftances, fix'oblong and narrow perforations: from the center there 
run five rays; they are oblong and narrow, and are formed, as in the others, of dou¬ 
ble rows, of pundtated perforations : when the fhell is recent, there ftand ieveral fe¬ 
ries of fine, {lender, and pointed fpines on it; but thefe are ufually loft, from the fhdls 
preferved in our cabinets. 
We haye it from the American iflands, principally from Barbadoes. 
Centronia fubglobofa flpinis aduncis fofciculatis. 
The roundifh Centronia, with crooked and faf 
ciculated fpines. 
3TJ)e 
applet 
This is one of the roundeft of this whole genus: the deprefied part at the iafe is 
fmall, and the reft of the figure is very regularly fpherical j the aperture for the mouth 
is at the bafe, and that for the anus at the fummit of the fhell. When we fee the 
fhell naked, as it ufually is, in our collections, we only can obferve a number of fmall 
papillae on it’s furface, thrown together in little clufters; but, when the creature is 
living, it is all over covered with little clufters of fpines; thefe are about a third of an 
inch in length, and are {lender, crooked, and pointed at the extremities : this is a very- 
rare fpecies. 
It is fometimes brought from the Mediterranean, but few of the {pines are pre¬ 
ferved. 
‘•-?V 
Centronia globofa fpinis aciculatis. 
The globofe Centronia , with needle-like fpines. 
Ojcll. 
This is one of the moft Angular of the whole genus; the body is almoft perfe&ly 
globofe j the apertures are one at the bafe, and the other at the fummit, and the whole 
Hell, as we ufually meet with it, which is without the fpines, is covered with very 
minute. 
