Pediculus aquaticus, 383 
Fig. 1. Plate XV. is an aquatic Infedt of 
which we have two Drawings and Accounts, 
both very fhort ; one in the Phil. Franfi. 288, 
the other in the Letters of Mr. Leeuwenhoek , 
Epijl. 121 : and as this Infect has no Name, 
I will venture to call it the Pediculus aquati¬ 
cus } for the Infedt to which Goedart gives 
that Name, is now allowed to be the Pulex 
arborefcens , or arboreus of Swammerdam. This 
Infedt is a common one, and of the cruda- 
ceous Kind, but being pretty tranfparent it 
is a beautiful Objedt in the Micro fcope* 
When it is fwimming it appears as fig. 1. It 
has five Pair of Legs; the firft Pair on the 
Side of the Head are the longed it has, the 
four other Pair are fhort and upon its Belly : 
the firft and fecond Pair are only vifible as it 
fwims.. The Back is guarded with large 
Scales which proceed all the Way to the Tail, 
but from the eighth Scale they are frequently 
covered fo thick with Hair, that only the 
Joints or Divifions are difcernable; but in 
other Poftures, as in N° 3, the Scales are 
vifible all the Way to the Tail. — The 
Tail is divided into two, with Hairs ifiuing 
from the Extremities of each Divifion, which 
in fwimming are kept extended as in fig. 
1. The Colour of this Infedt is a pale 
brown. 
Fig. 4. fhews the Infedt upon its Back, 
when all the Legs were vifible; only the 
three 
