326 SPECIES OF THE SYSTEMA. 
however, are of an uniform tint, so that the Lamarckian ex- 
pression “alba castaneo bizonata” is not at all appropriate to 
them. I have consequently deemed it advisable both to de- 
scribe and to figure (pl. 3, f. 6) the original specimens. 
Shell small, obliquely subglobose, depressed, not peculiarly 
solid, of an uniform reddish fulvous hue, very delicately sculp- 
tured, except in aged shells, which seem almost smooth, by 
close-set spiral raised strie, which, when highly magnified, ap- 
pear decussated by most minute and very obliquely con- 
centric striule. Volutions four, very convex: body-whorl not 
occupying more than five-eighths of the length, retuse beneath 
the very distinct suture, which is much arcuated, yet but 
slightly oblique, somewhat attenuated anteriorly; spire acute. 
Aperture large, expanded, obovate, decidedly longer than broad ; 
throat of the adult often stained with purple; outer lip forming 
an acute angle with the body, sharp at the edge; pillar lip very 
broad, concave, usually pale or whitish. Length two-fifths of 
an inch; breadth full half an inch. 
Cwrbs Revitowes, 
Linneus having referred us to a rude figure in Gualtier 
(45, F) of the Littorina cerulescens of Lamarck, which is not at 
variance with his brief and unsatisfactory description, Philippi 
rightly adjudged that the name Neritoides should be ascribed 
to that widely-diffused shell. The Linnean cabinet confirms 
the correctness of his views, for of its entire contents that 
species (Payraud. Moll. Corse, pl. 5, f. 19, 20, ZL. Basterotit) 
will alone agree with the pictorial and descriptive definitions. 
Gurbo littoreus. 
From the correctness of the synonymy no difficulty has ever 
been experienced in the determination of this species. The 
Littorina vulgaris, our common periwinkle (Chemn. Conch. Cab. 
vol. v. pl. 185, f. 1852, Nos. 1, 2, 3) is present in the typical 
collection, and alone agrees with both the pictorial and the 
