9 



the top, where the fhell fpreads into angulated points, 

 and is frequently as wide as at the bafe : the compartments 

 are irregular, thofe on the pofterior fide b road eft ; thefe 

 are fometimes wrinkled or ftriated longitudinally, others 

 are more fmooth, moft times white ; but a variety is of a 

 purplifli red; aperture large, infide margin ridged tranf- 

 yerfely : opcrculuvi of four rough valves but not ftriated, 

 angulated, ereft, forming four diftinft points a little re- 

 flexed. Height from half to three quarters of an inch ; 

 diameter at the bafe ufually much lefs. 



A variety of this fpecies with a more extended bafe, and 

 not fo much in height, has frequently been confounded 

 with the B. Balanoidcs : but the breadth of the aperture, 

 angulated margin, and quadrifurcated operculum are un- 

 erring marks of diftin6lion. We fhall here take the op- 

 portunity of remarking, that as the greater part of this 

 genus is fubjeft to great variety, and frequently run fo 

 much into each other as fcarcely to be diftinguidied by 

 common obfervation, it is neceffary to attend to the 

 operculum, which we have hitherto found an unerring 

 guide ; at leaft with refpeft to the Briti/Ii fpecies, which 

 in other refpefts approach each other in fome of their 

 varieties. 



For want of that attention to this eftential part, fo 

 much confufion has arifen, that it is difficult to place the 

 Synonyms to many of this genus. 



C Balanus 



