LEPAS. 43 



COMMON ACORN. 

 PL 7. /. 3. 



10. Lepas Balanus. L. testa conica sulcata, operculis acuminatis. Linn. 



Syst. Nat. ed. 12. p. 1107. Linn. Gmel. 1. p. 3207. 

 Shell conic and grooved : operculum sharp pointed. 

 Balanus sulcatus. B. testa conica truncata longitudinaliter sulcata, 



radiis transverse slriatis. Brug. Encycl. Meth. Hist. Nat. torn. 6. 



p. 163. 

 Lister, An. Ang. t. 5. f. 41. Ellis, Phil. Trans, vol. 50. t. 34. f. 17. 

 . Penn. Brit. Zool. ed. 1812. t. 40. f. 1. Chem. Conch. 8. t. 97. f. 820. 



Da Costa, Brit. Conch, p. 249. Donov. Brit. Shells, t. 30. f. 1. 



Mont. Test. Brit. p. 6. 



Shell of six valves, rugged at the edges : aperture not 

 large in proportion to the shell, which spreads much at 

 the base. Valves striated, sometimes sulcated longitu- 

 dinally. Operculum of four pointed valves, the two 

 smallest projecting beyond the others, which are trans- 

 versely striated, and divided by a longitudinal furrow. 

 Colour white, or greenish, or cinereous brown. Size 

 various, from a pea to a filbert. 



This species is found in clusters adhering to the 

 rocks on the coasts of Great Britain. It is common 

 also on the Greenland shore, and in the Mediterranean; 

 and will probably be met with on the rocky coasts of 

 most parts of the world. It has often been confounded 

 with the following species, from which however it is 

 sufficiently distinct. 



Pennant's fig. 3, of pi. 40. ed. 1812, is a variety only 

 of this shell. 



