290 BALANID.E. 



Affinities. — This noble Balanus, in all the characters derived from its 

 opercular valves, and from its cirri, is closely allied to the last species : 

 in the structure, however, of the shell and of the basis, it comes closer 

 to the following, B. Jlosculus. The crests on the under side of the 

 scutum, for the lateral depressores, are confined to these three species ; 

 and the crests for the rostral depressores are confined to B. imperator 

 and vestitus, but they are generally rudimentary in the latter. The 

 internal basal structure of the parietes is singularly like that of Chelonohia 

 caretta, though there is no other special affinity to that genus. In the 

 nature of basis ; in the structure, to a certain limited extent, of the 

 walls of the shell ; in the narrowness of the carino-lateral compart- 

 ments ; in the elongation of the third pair of cirri ; in the crests for the 

 rostral and lateral scutal depressores, B. imperator comes nearer to the 

 genus Tetraclita than does any other species of Balanus. 



40. Balanus flosculus. PI. 8, fig. 5 a — 5/. 



Shell purple or dirty white, tvith the internal basal edges 

 of the parietes rough tvith irregular points and ridges ; radii 

 narrow or absent; basis excessively thin, in appearance 

 absent. Scutum tvith crests for the lateral depressor muscle : 

 tergum very narrow, with the spur pointed. 



Var. sordidus. (PI. 8, fig. 5 b) shell globulo- conical, dirty white, 

 with numerous sharp, narrow, longitudinal folds or ridges. 



Hah. — Peru and Chile ; generally attached to the Concholepas Peruviana, or 

 to Balanus psittacus, and associated with Chthamalus scabrosus. Var. sordkhts, 

 inhabits Tierra del Puego, attached to littoral shells, wood, and rock, associated 

 with Ch. scabrostis. 



General Appearance. — Shell either extremely much depressed and 

 irregular, or globulo-conical, or more rarely cylindrical and elongated. 

 Walls, either with a few rather broad, smooth, irregular, longitudinal 

 folds, or, in var. sordidus, with numerous sharper and more prominent 

 longitudinal ridges ; basal margin very sinuous. Colour, either fine rich 

 peach-blossom purple, or so pale as to be almost white ; or in var. 

 sordidus dirty white, generally stained greenish from confervoid matter. 

 Orifice small, oval, entire. Radii very narrow, white, or not at all de- 

 veloped, and with even the sutures not distinguishable. The purple 

 coloured varieties, with the narrow white radii, the small oval orifice, 

 and folded walls, have a very pretty appearance, which is far from the 

 case with var. sordidus. The largest specimens attained a basal 

 diameter of *G of an inch, but this is an unusual size: I have seen a 

 cylindrical specimen of war. sordidus one inch in length. 



The opercular valves are united to the sheath by unusually strong 

 membrane : internally, their upper parts are stained purple. Scuta, 

 these vary considerably in breadth, some being even broader than in 



