INTRODUCTION. 



ii 



which I obferved in Rain-water, 

 that had fettled upon the Sands in 

 the Cavities of a low Shore near 

 Lijbon. I have alfo found them in 

 Fountain-water, at a great Diftance 

 from the Sea. 



The Fifli appeared in the Mi- 

 crofcope to be inclofed in a Bivalve 

 tranfparent Shell, refembling in Shape 

 that of a Mufcle : Its apparatus of 

 Horns or Arms it exerted, or re- 

 traced at Pleafure, opening its Shell 

 to an Angle of about thirty Degrees, 

 whenever it exerted them either for 

 the Formation of a Current attractive 

 of its Prey, or for local Motion, 

 which was either Progreffive or Cir- 

 cular. 



Thefe Phenomena, with fome others 

 in which they perfectly agree, I have 

 frequently obferved in thofe minute 

 oval Animalcules common in cor- 

 rupted Water, and have great Reafon 

 to think, that they differ in nothing 

 but Size. For altho , I cannot be 

 pofitive, that I have certainly feen 

 the bivalve Shell, in which I iuppofe 

 thefe Animalcules to be inclofed, and 



which 



