[ 231 ] 
which arife from fight and motion. Nature, from 
which they received an habitation fufficient to protect 
them from external injuries, feems to have fixed for 
^ life their abode to one dark fpot. Our bivalve infeds, 
on the contrary, by opening their two folding gates, 
enjoy both fight and motion, alternately dipping in . 
the mud, and darting though their element the water ; 
whenever they meet with bad company, they hide 
themfelves in their fhelis, and (hut up the valves, 
which force and diftrefs attempt in vain to force 
open. 
I have difcovered feveral different fpecies of thefe 
animals in the waters of Friderickfdal, one only of 
which is known to the naturalifts. Mr. "Baker, of 
the Royal Society of London, is the firft, that I 
know of, who mentions itj “ he fays^, that the 
infedl fwims very fail; that it procures its nourifh- ' 
‘‘ ment by means of a whirlpool, which it raifes in 
“ the water by means of its armsj that, upon meet- 
ing with a folid body, it flops itfelf by means of 
its feet; that upon the flighted: touch it fhrinks into 
“ its fhell ; and laflly that it bears much refemblance 
“ to a bivalve fhell-filh.” To this defcription he joins 
a figure, which, though imperfefl •f*, reprefents the 
infedl. Linnaiis J, and Geoffroi || call it the Mofiocky 
and without taking notice that Mr. Baker knew it 
already, they obferve that its antenna are compofed 
of fmall white threads ; and that the fhell is oblong, 
fmooth, and greyifh, round on one fide, flat on the 
* Microfcope made cafy. o. - * t*v " 
+ Tab. XV. f. viii. ' 
X Fauna Suecicay 1761; 2060. 
II Hiftoire des infedtes, tom. ii. p. 657. 4*. 
Other, 
