(sect, c), balanus amphitrite. 243 



more doubt regarding the last variety, cirratus, than on 

 any other, on account of its peculiar colouring, and from 

 the basis being often irregularly cup-formed. Under 

 B. concavus I have remarked how closely some of its 

 varieties approach to B. amphitrite, and it is to this last 

 variety that they approach ; almost the only difference being 

 that the scuta in B. concavus are longitudinally striated. 

 Yet some of the varieties of the two species are so distinct 

 that it would be puerile to class them together. I will 

 only add, that after studying such varying forms as B. tin- 

 tinnabulum and amphitrite it is difficult to avoid, in utter 

 despair, doubting whether there be such a thing as a dis- 

 tinct species, or at least more than half a dozen distinct 

 species, in the whole genus Balanus. 



As with B. tintinnabulum, I will first give a full descrip- 

 tion of the more common forms, alluding only to each less 

 frequent variation, and then separately describe briefly the 

 more marked varieties. 



General Appearance. — Shape conical, either steep or considerably 

 depressed ; sometimes tubular ; orifice either nearly entire or deeply 

 toothed, not large, varying from rhomboidal to rounded- trigonal. Sur- 

 face of shell smooth, never ribbed, generally naked, but occasionally the' 

 yellowish epidermis is persistent ; in the same individual, I have seen all 

 the lower part of the shell thus covered and the upper part naked, the 

 line of separation being defined. The colour varies much, even some- 

 times considerably on the same individual ; generally white or pale gray, 

 with dull violet-coloured, longitudinal, moderately broad stripes; these 

 stripes are sometimes equidistant, but more usually they are arranged 

 so as to leave broad white spaces ; the stripes fade away by endless 

 variations, the edges of the compartments and the carinal end of the 

 shell longest retaining any colour, until we have a uniformly white 

 shell, generally covered with a yellowish epidermis ; or the white 

 is longitudinally marked with hyaline lines ; this latter variety 

 has a very peculiar aspect, and I did not doubt it was specifically dis- 

 tinct, until, in a number of specimens on a ship from the West Indies, 

 I got the most perfect series, and another scarcely less perfect series 

 from the Mediterranean, graduating into common coloured varieties. 

 Rarely the dull violet or purple stripes become approximate and dark, 

 so that the whole shell is tinted of a brownish slate-colour, occasionally 

 freckled w r ith white. Again, we have another set of very pretty varieties, 

 with a white or very pale pink ground, with either narrow bright pink 

 or broad pinkish-purple stripes. Again, I have seen numerous speci- 

 mens of a variety, var. Stutsburi, from the west coast of Africa, in which 

 the upper part of the shell is white, and the lower part shaded with 



