(SECT. A), B ALAN US T1NTINNABULUM. 201 



Sowerby, also belong to this species. I further believe that a specimen 

 in SirC. Lyell's collection, given to him by M. Dujardin under the 

 name of B.fasciatus from Touraine, is likewise B. tintinnabulum. 



Varieties. 



With respect to var. communis, I have nothing to remark. The 

 second, var. vesiculosus (PI. 2, fig. 1 h), is confined to young specimens, 

 and may, perhaps, be due to a want of calcareous matter. With respect 

 to var. validus (PL 1, figs. 1 c, \f infra), I may observe that some 

 of the coarsest and strongest specimens which I have seen were said 

 to have been attached to a surface of iron. I have seen two large lots 

 of var. zebra (1 y), taken by Mr. Stutchbury, from the bottoms of 

 ships, arriving from Bengal and China, and in both cases associated 

 with var. communis, and in one case with var. coccopoma. I at first 

 thought that this variety, zebra, was specifically distinct, but now I 

 feel no doubt, that it is a mere variety ; its body was in every respect 

 identical with that of var. communis. 



Nor have I any doubt that var. crispatus, of Schrbter (PL 1, fig. h), 

 is only a variety, although the scuta in some specimens have a peculiar 

 appearance, externally like these valves in var. occator (PL 2, fig. 1 b): 

 the scutum is here broader and flatter than in var. communis, and the 

 adductor ridge is very feebly developed, but we shall see how variable 

 this ridge is in all the varieties : externally, the sharp, hood-like points 

 formed by the upturned lines of growth, have a very remarkable ap- 

 pearance, from being arranged in quite straight radiating lines. This 

 structure is evidently caused by the same tendency which produces on 

 the walls the sharp, upturned, irregular points ; but it is singular 

 that the scuta are smooth in some specimens with very rough parietes; 

 and, on the other hand, bristling with the symmetrically arranged, 

 hood-like projections, in other specimens on which I could with diffi- 

 culty detect only a few exceedingly minute points on the walls. In 

 var. communis I have seen a few specimens with a slight tendency in 

 the scuta to become striated longitudinally. The tergum in var. 

 crispatus presents no difference from that in var. communis. Some of 

 the roughest and best characterised specimens of var. crispatus appear 

 to have come off copper-sheathed, vessels. 



I believe var. spinosus of Gmelin (PI. 1, fig. i), has been correctly 

 considered by me as a variety, but Lhave unfortunately seen only one 

 set of specimens with their opercular valves preserved : these were 

 attached to Lepas anatifera. The colour of the shell varies from red- 

 dish-purple to nearly white ; the radii are sometimes quite white ; the 

 walls are slightly ribbed. The scuta in the above specimens, externally 

 were smooth ; the adductor ridge was rather more distinct from the 

 articular ridge than in any other variety ; and the terga rather more 

 plainly beaked. The tubular, up-curved, calcareous spines sometimes 

 occur only on one side of the shell, and often only in the lower part. 

 These spines are often coloured brighter than the walls. Their presence 

 cannot be accounted for (any more than the state of the scuta in the 



