/ [ 65 ] 
Univalves and Bivalves, the Multivalves not be^ 
ing yet exhibited to public View in their order; but 
the particularly curious may fee many fpecimens of 
them if they requeft it of the Officers of the Houfe. 
In the Remarks on this Colledtion of recent 
Shells, they will be taken in the order in which 
they are now depofited under their feveral Titles: 
A fmall defcription of each Kind, and the Names 
of a few of the molt remarkable Shells will be 
fufficient to anfwer our prefent Purpofe. 
One of the large Tables contains a Part of the 
Univalves, or Shells confifting of one Piece or Part. 
Echini Marini . Thefe are fometimes called 
Centronix and Cidares. The Sea Hedge-hog or 
Urchin, the Sea Egg, or the Sea Cake are the 
Names of the different Kinds of it in Englijh ; 
moftof them are of a globular Figure, fometimes 
with, at other Times without, fpines, befet with 
a great Number of regularly ranged Tubercles, 
and with Apertures more or lefs in Number, as far 
as fix or leven. Many of them are of a flat de- 
preffed Figure, when they are called Placentae or 
Sea Cakes, and they are not unfrequently inclined 
to an Oval Form, when they bear the Name of Sea 
Eggs. When the Fifh that inhabits this Shell is 
alive, it is generally armed with a great Number 
of Spines or Prongs, which are moveable at the 
Animal’s Pleafure, by means of Mufcles that com¬ 
municate with the Spines through the Papillae of 
the Shell : The Animal ufes thefe Spines both for 
its Defence and inftead of Legs to enable it to 
move from Place to Place. When the Fiffi dies, 
thefe Spines are very apt to fall off, which difco- 
vers the Papillae to which they were joined, and a 
great Number of regularly difpofed excrefcences 
on the outward Surface of the Shell, wherever there 
E was 
