25 



BALANUS. 



LEPAS TINTINNABULUM. Linn. 



Mawes Linn. f. 1 , pi. % 



La Marck in this Genus has only preserved such 

 shells as appeared univalves by the connection of their 

 valves in a peculiar manner, their lower part closed 

 with testaceous matter, and the operculum consisting of 

 four pieces. These Shells are usually of a conical form, 

 more or less elevated, sometimes narrower at the base, 

 in the form of a tulip; aperture subtriangular or ellipti- 

 cal; base closed by a solid testaceous termination, firm- 

 ly fixed to the substance on which the shell is attach- 

 ed; operculum consisting of four pieces or valves, in- 

 serted internally near the base. 



The increased growth of these shells in height and 

 circumference is easily perceived in each of its stages, 

 the one on Ihe conical part, and the flake or testaceous 

 separation at the bottom exhibiting the other. La 

 Marck conjectures that the animal, when necessity 

 obliges it to increase the size of its habitation, possesses 

 the faculty of detaching the parts forming its exterior, 

 and, after having added a giveu portion to each, fasten- 



