(sect, c), balanus nubilus. 253 



have a Balanus capable of living in fresh water, and likewise in the 

 saltest seas : even brackish water is a deadly poison to several, pro- 

 bably to most, species of the genus; but this, as we have seen, is not 

 the case with the allied B. eburneus. The water, I may add, at 

 Woolwich, on the Thames, whence I have received B. improvisus, must 

 at times be very brackish. I have already incidentally mentioned that 

 the var. assimilis was attached in great numbers, associated with B. 

 eburneus, tintinnabulum, aud amphitrite, on vessels from the West 

 Indies : one specimen sent me by Prof. Agassiz, from Charlestown, was 

 attached to a specimen of B. eburneus; and, lastly, I have seen three 

 sets of the same identical variety attached to shells from Guayaquil (in 

 Mus. Brit, and Cuming), and from West Colombia. Here, then, we 

 have the same species with an enormous range, from Nova Scotia and 

 Great Britain to South Patagonia ; and, which is the case with scarcely 

 a single mollusc, it lives both on the eastern and western tropical shores 

 of the South American continent. 



23. Balanus nubilus. PI. 6, fig. 2 a — 2 c. 



Shell white, rugged: basis in parts imperfectly porose. 



Scutum ivith the articular ridge ?ninute ; adductor ridge 



prominent, forming a deep pit for the lateral depressor 



muscle : tergum with an interned patch of purple ; apex 



produced, purple. 



Hab. — California, Mus. Brit, and Aug. Gould; associated with B. glandula, 

 and attached to wood. 



I have seen two specimens of this species, brought by 

 Lady K. Douglas from California ; and two from Monterey, 

 sent me by Dr. Aug. Gould. This is a very distinct species, 

 coming nearer to B. porcatus than to any other species : it 

 is also allied to B. cariosus. In the basis being in parts 

 solid or not permeated by pores, it has claims to be placed 

 in the next section, in which T at one time included it. 



General Appearance. — Shell conical, rugged, sometimes furnished 

 with sharp longitudinal ribs ; dirty white. Orifice not large, oval, 

 toothed. Radii rather narrow, with their summits oblique, much 

 jagged. Basal diameter of largest specimen 2'-l ; height only 1*3 of 

 an inch. 



Scuta, broad, with the lines of growth prominent; internally, 

 articular ridge very little prominent, sometimes hardly developed, 

 but thick, ending downwards in a small free point. Adductor ridge 



