202 BALANIDJE. 



foregoing var. crispatus) by the nature of the surface to which they 

 are attached ; for I have seen one set attached to a large rugged speci- 

 men of B. tinthinahulum, and another to the very smooth valves of 

 Lepas anatifera. I believe that this form is almost always associated 

 with var. communis, which is an argument that it is only a variety. 



To var. coccopoma (PI. 1, fig. d) I alluded in my introductory 

 remarks as having so strongly the aspect of a distinct species. I pos- 

 sess a beautiful group, with a globulo-conical, smooth shell, of the 

 finest rose colour, with a rather small, rounded orifice. These specimens 

 were attached (mingled with B. trigonus) to Avicula margaritifera, 

 from, as Mr. Cuming believes, Panama. I can never look at this 

 set of specimens without doubting the correctness of the determination 

 at which I have arrived. In the British Museum there are two sets of 

 specimens taken off a vessel, on the west coast of South America, 

 almost identical in external appearance with those in my possession, 

 but rather more rugged. Mr. Stutchbury has sent me some specimens 

 from a ship, direct from China, which are rather paler pink, and more 

 striped, and come near to some ordinary varieties of B. tintinnabidum. 

 The scuta (PL 2, fig. 1 /) in the above three sets of specimens agree in 

 having the adductor ridge more developed, and the pit for the lateral 

 depressor muscle deeper than is usual. The tergum (1 /, lo) in most, 

 but not in all these specimens, has a rather broader spur ; and some of 

 the specimens have the carinal portion of the basal margin considerably 

 hollowed out ; the spur, also, is placed nearer the basi-scutal angle than 

 in ordinary cases. On the other hand, in Mr. Cuming's collection, 

 there are two specimens taken off a vessel, identical in external appear- 

 ance with the foregoing, but which have scuta and terga in every 

 character exactly as in var. communis; hence I am compelled to con- 

 sider all these specimens as mere varieties. 



Var. concinnus (PI. 1, fig. e) is, perhaps, the most remarkable of all 

 the varieties ; I have seen three sets of specimens from the west coast 

 of South America, — all identical in appearance, having longitudinally- 

 ribbed walls, either rosy or of a dull purple, striped and freckled in a 

 peculiar manner with white. I have, however, seen an approach to 

 this colouring in some few specimens of var. communis ; and the shell 

 itself offers no other peculiarities. The scutum (PL 2, fig. 1 g) resem- 

 bles, in general shape, that of var. coccopoma ; but the adductor ridge 

 is here much sharper and more prominent ; and the rostral depressor 

 muscle, instead of being lodged in a little cavity formed by the folding 

 over the occludent margin, has, in addition, a small plate on the under 

 side, which tends to convert the pit into a tube. The tergum exactly 

 resembles that of var. communis. The segments in the sixth cirrus 

 bear six, instead of four, pairs of spines, — a circumstance which I have 

 noticed only in some young specimens oivar. communis, from the Cape 

 of Good Hope. From these several peculiarities, until quite lately, I 

 resolved to keep this form specifically distinct ; but I have finally con- 

 cluded that they are not sufficient. For firstly, I have seen a scutum 

 in var. communis (PL 2, fig. 1 d), with the adductor ridge nearly as 

 sharp ; and this ridge is always strongly pronounced in var. coccopoma ; 

 secondly, with respect to the plate for the rostral depressor muscle, 



