(sect, f), balanus dolosus. 295 



42. Balanus dolosus. PI. 8, fig. 7. 



Radii loith their upper margins oblique and smooth; 

 sutural edges smooth : basis permeated by large pores. 

 Tergum with the spur not very short, broad as one third of 

 valve. 



Fossil in Red and Maramaliferous Crag, England ; Mus. S. Wood, Bowerbank, 

 Lyell, J. de C. Sowerby, Henslow, &c. Mammaliferous Crag, Postwick, 

 near Norwich, Mus. Lyell. 



This species so closely resembles B. bisulcatus, both 

 externally and in all the essential characters of the parietes, 

 radii, and basis, that it is quite superfluous to describe 

 over again these parts. The specific characters are derived 

 from the opercular valves, which present well defined dis- 

 tinctions, found by me constant in several specimens of both 

 species. B. dolosus, like B. bisulcatus, has quite smooth 

 and deeply plicated varieties, often adhering to the same 

 univalve. The ribs on the inner surfaces of the parietes 

 are remarkably prominent. I think the upper margins of 

 the radii are in this species rather more oblique than in 

 B. bisulcatus. The sutural edges of the radii are marked 

 by the finest striae, representing septa. The sutural edges 

 of the alae are generally distinctly crenated. The basis is 

 often slightly cup-formed, and very plainly porose : its 

 surface is marked by radiating ridges. The orifice of the 

 shell is large, and elongated, especially in young specimens. 

 The basal diameter of the largest specimen is 4 of an inch. 



The Scuta have no trace of the two or three longitudinal furrows so 

 conspicuous on these valves in B. bisulcatus, and which, in that species, 

 run down from the apex of the valve ; this fact showing that the furrows 

 occur in quite young individuals. The whole valve is not quite so narrow 

 as in B. bisulcatus, but otherwise agrees with it in shape : internally, 

 there is hardly any difference : the articular furrow is not so wide : the 

 articular ridge is very prominent, and abruptly truncated at its lower 

 end : the adductor ridge is also prominent; it here runs a little higher up 

 the valve than in B. bisulcatus. The Tergum differs more in the two 

 species : the spur is not so broad ; measured in its upper part, it is 

 only about one third of the entire width of the valve, instead of being 



