X Introduction. 



and Bryum, One of which Corallines is exhibited at B, 

 Plate III. and another at 5, Plate V. 



And for want of examining thefe Corallines, as I may fay, 

 alive in their proper Element the Sea-water, others likewife 

 had formed erroneous Opinions concerning them, as well as 

 myfelf : Some imagining thefe little Veficles only to ferve as 

 fwimming Bladders, like thofe in the Acinaria or Gulph- 

 weed, and the ^ercus Marina or Sea-Oak. 



There are two of thefe Veficles, with the larger Polypes 

 in them expreffed, magnified near the Middle of the Fig. J, 

 in Plate V. 



Thofe are called Denticles, that look like Teeth, and are 

 placed oppofite to each other on the Sides of the Stem and 

 Branch of the fame Figure. 



Thefe larger Polypes are united below by a tender thread- 

 dy Line, to the flefhy Part that occupies the Middle of the 

 whole Coralline. 



In fome Inftances, we may obferve, that thefe Animals 

 are wrapt quite round in their Veficles, during their Embryo 

 State, like thofe in Plate XI. Fig. C. As thefe advance in 

 Size, and grow towards Maturity, the Top of the Veficle 

 begins to open, the Animal ftretches itfelf out, and dif- 

 plays its Arms about in Search of Food ; and when it is in 

 the leafl: difturbed, it fuddenly contrads itfelf to the Bottom 

 of the Veficle, which clofes after it at the Top. 



Some Species of Corallines have little elaftic Opercula or 

 Covers to their Veficles, to fecure the Mouth or Entrance 

 of the Veficle upon the Animal's Retreat to the Bottom of it. 



as in Plate III. Fig. B, 



Thefe 



