3$o A Letter from a Friend , &e. 
It is fhewn at M in the Pofture of fwimming, 
at which Time it moves pretty fwiftly With' 
its flat Head foremoft : its Tail appears di¬ 
vided, and on each Side it extends a fpread- 
ing Fisa. At N it is fhewn in Profile, and 
with its Fins drawn in, as ufually is the Cafe 
when it appears at reft. 
*Tis about the Size of the largeft Animal¬ 
cules found in the Infuftons of Hay in Water. 
CHAP. XXVII. 
A Letter from a Friend, containing many 
curious Microfcopical Obfervations, 
M ANY of the Drawings in Plate XV, 
together ■with the Defcriptions of 
them, were lent me by a Gentleman, whofe 
true Judgment in the Ufe of the Micro- 
fcope, and the Accuracy of whofe Pencil in 
delineating therefrom, I have been long ac¬ 
quainted with : and whofe Name, had I 
Heave to mention it, would do great Honour 
to this Work, as his Friendship does to the 
Author of it. As it is therefore neceffary 
to give his Defcription of thefe curious'Sub- 
jedts in his own Words, I hope it may be 
excufable to puhlifti the whole Letter where¬ 
in they are inferred, though written with the 
kind Partiality of a Friend, 
8 I R ? 
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