BALANUS 



Nothing can be more variable in general form than 

 the Balani ; for when they are placed upon a smooth and 

 even surface they become of a, pretty regular, rather 

 obtusely conical shape; if, on the contrary, they are 

 placed on an uneven and rough surface, their form 

 is so far governed by their situation, that they become 

 more or less irregular according to the degree of uneven- 

 ness of the surface to which they are attached: when 

 they are grouped, which is most commonly the case, they 

 sometimes become very much and irregularly elongated, 

 clavate, fistulose, &c. Each Balanus consists of six 

 valves, four of which are nearly equal in size and larger 

 than the remaining two, and all united together by their 

 sides, so as to form a more or less regular cone, whose 

 apex is open and base closed by a testaceous valve, by 

 which it is attached; and it is remarkable, that even when 

 Balani are united together by their sides, it is generally by 

 a lateral extension of this base and not by any part of the 

 six valves which form the cone. The posterior pair of 

 lateral valves arc the smallest. The operculum, as in 

 Conia, is bipartite, but it consists of four valves, of which 

 the posterior pair is rather the more prominent. 



The Balani, than which perhaps no genus of shells is 

 more common, abound on all kinds of bodies that are at any 

 time covered by the sea : we believe that there are many 

 distinct species, of which, indeed, we have several on our 

 own coasts ; those that are found imbedded in sponges have 

 generally a cup-shaped base, and form the Genus Acasta 

 of Leach: another sort which has generally an elongated, 

 lanceolate base is found attached to and overgrown by 

 various species of Gorgoniae ; this is the Balanus galeatus 

 of Lam, and the Parrot's-bill Lepas of Ellis. 



There are also many distinct fossil species, but they 

 are only found in the newer strata : we have them from 

 Fiacenza, Bordeaux, Paris, Essex, &c. 



Fig. 1. Balanus Tintinnabulum var. 



2. spinosus. 



3. circinatm^ Defr. Diet, des Sciences Nat. 



4. Montagiii, Acasta Montagni, Leach. 



5. A variety of the same without spines and having a flat ba§e. 



6. Balanus galeatus. Lam. coated by a Gorgonia. 



7. The same uncoated. 



8. A small variety of the same from another species of Gorgonia, this is 

 exceedingly variable in shape. 



