LEPAS STRÖMIA. _O. Müller._ Zoolog. Dan. Prod., No. 3025, 1776.
---- ---- _Ib._ Zoolog. Dan., vol. 3, Tab. 94, 1789.
---- STRIATA. _Pennant._ British Zoology, vol. 4, Tab. 38, fig. 7,
1777.
DIE WARZENFORMIGE MEEREICHEL. _Spengler._ Schriften der Berlin.
Gesell., 1 B., Tab. 5, fig. 1-3, 1780.
LEPAS VERRUCA. _Spengler._ Skrifter af Naturhist. Selskabet, 1 B.,
1790.
---- ---- ET STRÖMIA. _Gmelin._ Syst. Nat., 1789.
BALANUS VERRUCA. _Bruguière._ Encyclop. Meth., 1789; _Clisia
verrucosa_, Deshayes, in Tab.
---- INTERTEXTUS. _Pulteney._ Catalogue of Shells of Dorsetshire,
1799.
LEPAS STRIATUS. _Montagu._ Test. Brit., 1803.
---- VERRUCA. _Wood's_ General Conchology, Pl. 9, fig. 5, 1815.
VERRUCA STRÖMII. _Schumacher._ Essai d'un Nouveau Syst. Class., 1817.
CREUSIA STRÖMIA ET VERRUCA. _Lamarck._ Animaux sans Vertèbres, 1818.
OCHTHOSIA STROEMIA. _Ranzani._ Memoire di Storia Nat., 1820.
CLISIA STRIATA. _Leach._ Encyclop. Brit. Suppl., vol. 3 (sine
descript.), 1824.
CLITIA VERRUCA. _G. B. Sowerby._ Genera of Recent and Fossil Shells,
Plate.
VERRUCA STRÖMII. _J. E. Gray._ Annals of Philosophy (new series),
vol. 10, Aug., 1825.
_Moveable scutum, with the lower articular ridge not half as broad as
the short upper articular ridge: shell generally ribbed longitudinally._
_Var., with the shell not longitudinally ribbed._
_Hab._--Shores of Great Britain and Ireland, Shetland Islands;
and, according to various authors, Denmark, Iceland, and shores of
northern Europe. Red Sea, Brit. Mus. Attached to shells, laminariæ,
rocks, crabs, and floating bark, from low tidal mark to fifty or
ninety fathoms.
_Fossil_ in Glacial deposits of Scotland, Mus. Lyell; Red Crag
(Walton, Essex), Coralline Crag (Sutton), Mus. S. V. Wood.
I have given so full a description of the genus that little remains
to be said under the species. Generally the whole shell is covered
(independently of the interfolding, oblique, articulating plates) by
narrow, longitudinal ridges or folds; and by this character alone the
ordinary variety of _V. Strömia_ can be distinguished (as far as I
have seen) from all the other species. The shell is white or dirty
yellowish-brown. The scutum has the lower articular ridge on its tergal
margin very narrow (but somewhat variable in width), appearing like a
mere slight shoulder, against which the longitudinal axial ridge of
the tergum abuts: it is not half as wide as the short, upper articular
ridge. On the under side there is a very slight depression for the
adductor scutorum muscle. There is considerable variation in the degree
to which the transverse ledge on the under side of the fixed tergum
projects, and therefore in the depth of the hollow thus formed. The
specimens with the right-side, and those with the left-side opercular
valves moveable, are apparently about equally numerous.
The specimen in the British Museum, from the Red Sea, was attached
to a Gorgonia, and was in the same box with a Pyrgoma--circumstances
favouring the correctness of the locality--but I am much surprised
from the general distribution of the species, that _V. Strömia_ should
occur in so distant and isolated an area. After careful examination,
I can discover no constant difference between the Red Sea and British
specimens.
The specimens from the Crag have not their moveable opercular valves,
which offer much more important diagnostic characters than the shell;
but as far as the latter is concerned, no difference whatever can be
perceived from _V. Strömia_.