16 INVERTEBRATA OF MASSACHUSETTS. 



Adheres in clusters to floating wood, to shells, Crustacea, &c. 

 It may be obtained almost any time at a lobster-stand. It often 

 attains a much larger size. 



It differs from all other described species in having its surface en- 

 tirely without ribs. In its earliest stages, B. ovularis is also smooth, 

 and similar in shape to the young of this species ; but even then, this 

 shell exhibits its triangular aperture, while the other is diamond- 

 shaped. B. ovtildris and B. Icevis of Lamarck, though both described 

 as smooth, are both said to have delicate ribs. The first is also de- 

 scribed as cylindrical; while the second is said to have a contracted 

 aperture. Mr. Sowerby states that he is unacquainted with it. It 

 appears not to be an uncommon or a local species, as I have taken it 

 from the bottom of a ship of war from the West India station. 



BAlanus rugo'sus. 



Shell ichite, sub •cylindrical, valves raised into angular points ; 

 icithout, coarsely and irregularly ribbed ; aperture large, rhomboid- 

 al ; operculum nearly smooth, ivith acute, curved, slightly diverging 

 points. 



Figure 10. 



State Coll., No. 289. Soc. Cab., No. 2311. 



Lepas borealis, Donovan ; Brit. Shells, v. pi. IGO. 

 Lepas rugosa, Wood ; Gen. Conch., 41, pi. 6, f. 4. 

 Balanus rugosus, Montagu ; Test. Brit., 8. Dillwyn ; Catnl., 17. 



Shell white, erect, cylindrical, or somewhat conical, but usually 

 as broad at summit as at base, and its height frequently exceeding 

 its diameter. Summits of the valves rising into acute, spreading 

 points, the posterior one folded and curved into a beak ; exterior 

 very rough, with coarse, unequal, flexuous folds or ribs ; the de- 

 pressed areas small, smooth, and shining. Interior slightly grooved 

 at base, otherwise smooth. Aperture large, diamond-shaped ; 

 valves of the operculum rising into acute, diverging points ; the 

 separated portions distinctly striated from before backwards ; 

 surface smooth, or delicately wrinkled from side to side, margins 

 direct. Diameter of base sometimes | inch. 



Of these I found fine specimens on a pine log lying upon the 

 beach at East Boston. But they are usually obtained further 

 northward, seated upon Pecten Islandicus, Fusus Islandicus, &c. 



