260 
Fig. 4. 
Ihe Natural Hiftory of the Book IX. 
which, juft before, when feeding, were of an Inch Diameter, is in an 
Inftant contracted, like the Mouth of a Purfe drawn together ; and be- 
comes of a blunt conic Form, the Bafe being the Part fixed or clinging 
to the Rock. 
Its Appearance, in this its quiefcent State, is reprefented in Plate X. 
There is likewife a lefs Sort, of the fame Species with the Hbeve. 
defcribed, differing chiefly in Colour, which of the fmaller Kind is 
black. 
OF 
