Of the Barnacle. 97 



other in fuch a Manner, that the 

 Animal enjoys the Advantage of 

 drawing in freih Water and Food, 

 not by caufing the two Sides to 

 recede, as Oyfters and Mufcles do, 

 (which is prevented by a curve con- p ^ elI « 

 cave Hinge, into which their Edges 3 * 

 are inferted, extending to more than 

 half their Circumference) but by 

 forming Angles at each Divifion, Fig. 1, *. 

 in fuch a Manner, as to give the 

 Aperture nearly the Figure of a 

 Rhomboid. Thus whatever is at- 

 tracted by the play of its Horns, 

 is eafily retained within the Cavity ' 

 which the Valves form ; and 

 as when the Animal is undifturbed, 

 the Shell is conftantly open, it en- 

 joys a continual Supply of frefh 

 Water, which it alternately fucks 

 in, and ejects. This Aftion appears 

 when the reft of the Apparatus is 

 at Reft, by the Play of two cor- 

 refponding Antennse, refembling thofe 

 of fome Infedts, which nearly keep 

 Time with the Motion of the Gills 

 in other Fifth. 



The Head of the Fifti is fur- 

 : ni(hed with an Apparatus of Horns j£f VL 

 H to 



