B22 
MOLLUSCA. TROCHUSIDJE. 
Trochus, 
Breadth about an inch, height one-fourth less ; variously marked with 
red, blue, and white ; base slightly convex ; whorls spirally striated ; the 
upper part of the two last waved or tuberculated, and a raised rib round the 
base of each; pillar cavity wide, with an open spiral groove. — Specimens of 
a shell exactly corresponding with Turbo carneus of Mr Lowe (Zool. Journ. 
vol. ii. p. 107 . t. V. f. 12. and which Mr Gray has identified with the Marga-- 
rita striata of Leach (Boss’s Voyage of Discov. App.), Zool. Journ. vol. ii. 567.), 
which I found plentifully in Zetland, were sent to Mr Montagu in 1809, who 
pronounced them the fry of a Trochus. There can be little doubt of their 
relation to the present species. 
282. T. umhilicatus . — Spire bluntly^ conical ; whorls nearly 
even, obsoletely striated at the base. 
T. crebris striis fuscus. List. An. Aug. 1669. t. hi. f. 15. Conch, ncxli. 
f. 31. — T. umbilicaris, Penn. Brit. Zool. iv. 126 — T. cinerarius, Don. 
Brit. Shells, t. Ixxiv. three middle figures. — T. umbilicatus, ilfow^.Test. 
Brit. 286 — On Fuci near low water-mark. 
Breadth |ths, height fths of an inch ; whitish, with waved purple stripes. 
Whorls five, imperfectly marked by the separating line ; striated, smooth ; 
pillar cavity with sloping wrinkled sides ; the margin of the cavity and of 
the body whorl rounded. 
288. T. cinerarius. — Spire subdepressed, with a minute 
apex ; whorls with a well defined separating line ; strongly 
striated at the base. 
Penn. Brit. Zool. iv. 1 27* Don. Brit. Shells, t. Ixxiv. two upper and 
two lower figures. Mont. Test. Brit. 284 — Near low water-mark. 
Height and breadth about |ths of an inch ; grey, with numerous lines of 
purple ; whorls five ; strongly striated, the striae interrupted by the lines of 
growth, giving the surface a rough feel ; pillar cavity large : the tentacula 
and lateral filaments not so dark nor so strongly marked with annular rings 
as the preceding. — I am not satisfied with the claims of this species as dis- 
tinct from the preceding. They are probably only varieties constituting the 
Trochus cinerarius of Linnaeus. 
284. T. tumidiis . — -Whorls subquadrangular, with numerous 
spiral stri^ slightly decussated by the lines of growth. 
Mont. Test. Brit. 280. t. x. f. 4. 4. — In deep water. 
Length about i%ths, and breadth about i%ths of an inch ; dusky white 
with spotted transverse lines of purplish-brown ; whorls five, flat at top, 
nearly even on the sides, or rather slightly concave, with the lower edge 
subcarinated ; base a little rounded, the lines of growth diverging from the 
pillar cavity, which is variable in size.. — The Trochus umbilicatus of Walker 
(Test. Min. tab. ii. f. 58.) is considered as referable to this species. 
The Trochus cinereus of Ha Costa (Brit. Conch. 42. t. iii. f. 9, 10.), List. 
Conch, t. pcxxxiii. f 21. ; Don. Brit. Shells, t. civ, f. 2, has not occurred to any 
other collector of British shells. He states it as common on many parts of 
the coast. The species, however, to which he refers, is of foreign growth, 
and readily distinguished by its concave base, wide pillar cavity, and jagged 
pillar lip. 
Pillar closed. 
285. T. Whorls five, rounded, wrinkled ; the pil- 
lar lip with a blunt tooth. 
