(sect, a), balanus vinaceus. 213 



with their summits oblique ; their sutural edges are barely crenated. 

 Basis, thin, flat, or cup-formed. Body unknown. 



Affinities. — In general appearance this species comes near to B. 

 psittacus; but in all essential characters it comes much closer to the 

 following species, from which, however, it can easily be distinguished 

 by colour, and by the inner lamina of the parietes not being cancellated. 



7. Balanus vinaceus. PL 2, fig. 7 a — 7 d. 



Shell purplish dark brown : inner lamina of the parietes 

 cancellated. Scutum finely striated longitudinally. Tergum 

 with the longitudinal furrow shalloio and open; basal margin 

 on both sides sloping towards the spur. 



Had. — West Coast of South America. Mus. Cuming 



&• 



General Appearance. — Shell conical, with a large, rhomboidal orifice; 

 walls rather thin, coloured, together with the radii and operculum, dark 

 purplish-brown ; sheath nearly colourless. Walls smooth, slightly 

 irregular, very finely striated longitudinally. Basal diameter of largest 

 specimen # 8 of an inch. 



Opercular Valves, unusually smooth, that is without prominent 

 growth-ridges. Scuta, finely striated longitudinally, with the sharp 

 striae closely approximate. The teeth on the occludent margin are sharp, 

 and stand some way apart from each other. Internally, the whole 

 surface is remarkably flat and smooth : the articular ridge is of mode- 

 rate breadth, and slightly reflexed : there is no adductor ridge, and the 

 oval depression for the lateral depressor muscle is extremely slight. 

 Terga, with the longitudinal furrow very slight ; the bottom of this 

 furrow is feebly striated longitudinally, and there is a trace of a fine, 

 rounded ridge on the scutal margin, as in B. decorus. The basal margin 

 slopes on both sides towards the spur, which is of moderate length and 

 breadth, with its lower end truncated and parallel to the carino-basal 

 margin ; the spur stands at about once and a half its own width from 

 the basi-scutal angle. Internally, the valve is lined by very dark, 

 purplish-brown corium ; the articular ridge is prominent ; in the upper 

 part of the valve, parallel to the articular ridge, there are two or three 

 feeble ridges ; there are no crests for the tergal depressores. 



The Parietes, though moderately thick, yet are light and fragile ; the 

 denticuli at the bases of the longitudinal septa are prominent, and those 

 on the adjoining septa are united together, making a net-work (PI. 2, 

 fig. 7 d), but the interspaces between them are not filled up by solid 

 calcareous matter (as is the case with every other species of the genus), 

 but are only crossed at successive levels by fine transverse calcareous 

 septa; the internal lamina thus becoming cancellated, and, though 

 thick, fragile. Hence, in a transverse section of the parietes, the 

 ordinary parietal tubes or pores are seen to be lined on their inner sides 



