BALANUS. 17 



4. Balanus concavus, Tab. I, fig. 4« — 4p. 



Balanus concavus. Bronn. Italiens Tertiar-Gebilde (1831) et Lethsea Geognostica, 

 b. ii, s.1155 (1838), Tab. 36, fig. 12. 1 

 — cylindraceus, var. c. Lamarck. Animaux sans Vertebres (1818). 

 Lepas tintinnabulxjm. Brocchi. Conchologia Sub-Appen., t. ii, p. 597, (1814). 



B.joarietibus et basi, sed non radiis ports perf oralis ; testa alio cum roseo aut obscure 

 purpureo longitudinaliter pictd, interdum pure alba. Scuto longitudinaliter tenuiter striato : 

 interne, adductoris crista admodum aut modice prominente. 



Parietes and basis, but not the radii, permeated by pores ; shell longitudinally striped 

 with white and pink, or dull purple ; sometimes wholly white ; scutum finely striated lon- 

 gitudinally ; internally, adductor ridge very or moderately prominent. 



Fossil in Coralline Crag, (Ramsholt and Sudbourne) rarely in the Red Crag (Sutton) ; Mus. 



5. Wood, Bowerbank, Lyell, J. de C. Sowerby, Tennant. Sub-Appenine formations, near Turin, Asti, and 

 Colle in Tuscany, Mus. Greenough, &c. Tertiary bed, near Lisbon, Mus. D. Sharpe and Smith. Bordeaux (?) 

 Mus. Lyell. Tertiary beds, Williamsburg; and Evergreen, Virginia, Mus. Lyell. Maryland, Mus. Krantz. 

 Pleiocene formations 2 near Callao, Peru, Mus. Darwin. 



Recent at Panama; Peru; S. Pedro, California; Philippine Arch.; Australia. 



This species has caused me much trouble. It will be convenient first to make a few 

 remarks on the recent specimens ; I examined several from Panama and California, which, 

 though differing greatly in colour, resembled each other in their scuta having the adductor 

 ridge extremely prominent, and in having (Tab. I, fig. 4>n) an almost tubular cavity for 

 the attachment of the lateral depressor muscle, — characters which at first appeared of high 

 specific value ; but I soon found other specimens from Panama in which these peculiarities 

 were barely developed. I then examined a single specimen from the Philippine Archi- 

 pelago, resembling in external appearance one of the Panama varieties, but differing in the 

 scuta being externally strongly denticulated in lines instead of being merely striated, — in 

 the adductor ridge being far less prominent, — and in the spur of the tergum being broader 

 and more truncated ; I therefore considered this as a distinct species. I then examined a 

 single white rugged specimen from the coast of Peru, which differed from the Philippine 

 specimen in the shape of the well-defined denticulations on the scuta, and in some other 

 trifling respects, and in the segments of the posterior cirri bearing a greater number of 

 spines ; with considerable doubt, 1 also named this as distinct. But when I came to 



1 I suspect that B . pustularis, miser, and zonarius, all figured by Minister, in his ' Beitrage,' b. iii, 

 Tab. 6, may be this species. 



2 I procured this specimen from the Island of S. Lorenzo, off Callao ; it was imbedded, together with 

 seventeen species of recent shells and with human remains, at the height of eighty-five feeL 



3 



