APTE RA» 
This inleft is particularly curious on account of the 
formation of its arms, and the motion it makes with 
them in the water. By means of thefe, the little crea¬ 
ture can move in any direftion, waving them as a bird 
does its wings. They iometimes remain feveral days 
on the furface of the water, at other times are feen 
only at the bottom ; but whether at the bottom or 
the furface they are con ft ant ly in motion. The mo¬ 
tions are very rapid, fo that the little animal appears 
as if jumping in tne water ; its head always tending to 
the furface, and its tail ftretched downwards. Some 
call it the Water-Flea , but that name is likewife ap- 
plied to the gyrinus, a black infeft of the ftrft order, 
Monoculus 0 uadricornis . 
Lefs than half a line in length ; its antennae ap~ 
peal Alice branch . the animal- carries its esters on the 
two rides of its tail ; the feet are placed under the 
body, but it makes little ufe of them ; the antennae 
being of more feryice toward the leaping and £ki-p. 
ping, which it performs in the water with great nim¬ 
bi enefs. 
Found in ftandirig pools : other i rife ft s and polypi 
feed upon them. 
Monoculus Conckareus. 
The fliell monoculus. 
• , ; 
This is provided with a bivalvular fhelf; within 
which ne fhuts himlelf up if drawn out of the water. 
I 2 The 
