S. zonalis.
S. violacescens.
S. gædaropus. The thorny red Spondylus. Pl. [15], fig. 1.
Upper valve red, under one white, with longitudinal striæ or ribs; rough granulations, and somewhat tongue-shaped; rather short truncated spines.
S. longispineus. The long-spined Spondylus.
Thickly spined, longitudinally sulcated and ribbed; alternate spines arcuated and tongue-shaped; valves of a reddish colour; umbones orange.
7. Podopsis. Two fossil species.
Only introduced here to fill up the family and keep up the chain of connexion. It approximates the genus Gryphea.
Shell rather thick, sub-regular, symmetrical, equilateral, inequivalve, adhering by the extremity of the shorter valve; the other terminated by a summit pointed, a little recurved and medial; articulation very angular, by means of two very distant condyles.