OCTOMERIS ANGULOSA. 483 



1. OCTOMERIS ANGULOSA. PI. 20, fig. 2 «— 2 b. 



Octomeris angulosa. G. B. Soicerby. Zoological Journal, vol. 2, 



July, 1825. And Genera of Recent and 

 Fossil Shells, Plate. 



— Stutchbukii. /. & Gray. Annals of Philosophy, new 



series, vol. 10, August, 1825. 



— AUGTJBRA (?) Chenu. Illust. Conch., Tab. 4, fig. 2. 



Shell dirty white, rugged and massive : aim thick, with their 

 sutural edges coarsely crenated. 



Hab. — Algoa Bay, Cape of Good Hope. Attached to littoral rocks ; often 

 associated with Balanus Capensis and Chthamalus dentatus; Mus. Brit., 

 Cuming, Stutchbury, Bowerbank. 



General Appearance and Structure of Shell. — Shell extremely rug- 

 ged, irregular, massive, generally much corroded, steeply conical 

 or even sub-cylindrical : orifice large, broad, rhomboidal, of nearly 

 equal breadth at both ends. Colour dirty white, often slightly tinted 

 yellow from the investing membrane, and from thin layers of punctured 

 membrane alternating with the laminae of shell. The parietes, in old 

 specimens, have very irregular longitudinal ridges, or rather plates 

 projecting out, sometimes much branched, and generally curved 

 inwards so as to meet each other, thus forming round the basal margin 

 a circle of cylindrical apertures. In old large specimens the radii are 

 not developed, and till the compartments are disarticulated there is no 

 trace of the toothed structure of their sutural edges : in this condi- 

 tion the sutures exist as deep, rugged, narrow fissures. In younger 

 shells, the radii, though narrow, are distinct, and have their surfaces 

 transversely ribbed, and their edges toothed and interlocked with the 

 teeth of the recipient furrow. Some of the specimens present a 

 curiously deceptive resemblance to Elminius plicatus. Basal diameter 

 of largest specimen, one inch and a quarter ; height one inch. 



The parietes are remarkably thick, but the compartments separate 

 easily : I have, however, seen one instance in which they were partially 

 calcified together. Their internal surfaces are very smooth. The sheath 

 does not descend low. Thealse project rectangularly ; they have thick 

 edges, and these are coarsely crenated in transverse lines. Of the radii 

 sufficient has been said. 



Scuta (fig. 2 b) : these, in all the specimens seen by me but one, have 

 been deeply corroded, and their outline, as in Chthamalus, considerably 

 modified : in the one specimen well preserved, the exterior growth- 

 ridges were extremely prominent. The articular ridge does not project 

 much, nor is the articular furrow very deep. There are more or less 

 distinct crests for the lateral depressor muscles. The Terya are rather 



