young from their Tails, I do not remember that I e- 
ver obferved any thing of them but what a good and 
full accouat is given of in a Book ^irdtu\cdGamri;.arola^ 
gia, of Phil. jac. Sachs Ihewed me by Dr Plot ^ 
if upon perafal of that Book , any thing occurs 
that you defire farther fatii^fadion in, I fliall be ready 
to give you the beft information I -can, if you fend a- 
ny Qiieries to 
Jof^r Hnmble Serva?it^ 
Ch. King- 
IV. Part of UonfieuY PoupartVc Letter to Dr 
Martin Lifter, B. R. S» concerning the InfeEt 
called Libella. 
IT is a flying Infed, called in France Demoifelle^ from 
the variety of its Colours, tranfparency of Wings, 
and its ftately Flight : They alfo call it Perle^ from the 
figure of its Head, or rather from the roundnefs and 
colour of its Eyes. It is called by the Latins Libella^ 
perhaps becaufe in flying it carries its Body Horizon- 
tal 3 not that it does fo aUvays, for it is divided from 
fpace to fpace into rings, by means of which, it com- 
pofes Angles with its body, v/hofe lines it can make 
longer or fliorter as it finds occafion. Tiiefe different 
feftions ferve to the motion of this Infeft, as we know 
the Tail doth in Birds, and as they are lengthened or 
contrafted, they carry themfelves according to their 
various inclinations, the point or center being fixed be- 
tween their Wings. All Modern Natural ifts know that 
the great fort ot LihdU are generated under 
water, wrapt up in a Membrane, which at length dif- 
foives and turns to nothing* This Phenomenon is not 
