312 MOLLUSCA. PECTIN IBRANCHIA. Scalakia, 
most prominent, llibs distant, circular. Length an inch and a half, breadth 
about half an inch. — Sower. Min. Conch, t. xvi. two upper figures. — In Crag.^ 
from Bramerton. 
2. S. semicostata. — Whorls about 7i contiguous ; spire transversely striated, 
ribs numerous, but slightly raised, lower part of each volution smooth, naked. 
~~-Soiver. Min. Conch- t. xvi. middle figure. — In London Clay^ from Barton 
Cliff, and in Crag of Suffolk, {Ib. t. 390.) 
3. S. acuta. — Whorls about 7, rather distant ; spire with three slight trans- 
verse risings, and a fourth very prominent one, near the lower part of each 
turn. Bibbs recurved, expanded, and acutely angular at their upper ends ; 
outer lip produced retrally., — Sower. Min. Conch, t. xvi. lowest figure.— In 
London Clay., Barton Cliff 
4. S. subulata. — Whorls contiguous; ribs 10 or 12, thick, reflected ; the in- 
tervening spaces smooth. — Sower. Min. Conch, t. cccxc. f. \.->-Crag., Suffolk. 
5. ^.foUacea. — Whorls separate ; ribs distant, slender, broad, leaf-like, re- 
flected in the middle. — Sower. Min. Conch, t. cccxc. f. 2. — Crag^ Suffolk. 
6. S. minuta. — Whorls contiguous : ribs about 20, thin, obtuse, elevated. — 
Sower. Min. Conch, t. cccxc. f. 3, A.— Crag., Suffolk. 
Gen. LIII. CYCLOSTREMA. ~ Spire short; transverse 
ridges on the body-whorl disjoined from the pillar by a 
crenulated groove. 
S62. C. Zetlandica. — Shell conical; whorls 5, ribbed spiral- 
ly and transversely, with angular tubercles at the points of de- 
cussation. 
Mont. Linn. Trans, xi. 194. t. xiii. f. 3 — Zetland. 
Length 2 lines ; Vhite ; apex obtuse ; whorls tumid ; longitudinal ridges 
do not extend to the lower part of the body -whorl, where the spiral ridges 
are very prominent ; aperture nearly orbicular, and marginated. A single 
example of this species occurred to me among shell-sand at Noss, Zetland. 
It was lent to my valued correspondent the late Mr Montagu, who omitted 
to return it, so that I can add nothing to the description which he has pub- 
lished. 
Gen. LIV. DELPHINULA. — Spire depressed, produced, 
and tuberculated. 
263. D. calcar .—'W\\ov\^ 4, the upper ones depressed, form- 
ing a flat summit. 
Mont. Test. Brit. Sup. 137, t. xxix. f. 3 — On the shore of Iona, Mr 
Laskey. 
Breadth about a quarter of an inch ; of a pale pink colour ; round ; on the 
body and part of the second whorls are large, smooth, lanceolate spines, ra- 
diating in straight lines from the shell, about 13 in number ; base convex, 
with a central cavity ; aperture orbicular. 
EXTINCT SPECIES. 
1. T>. coronata . — Discoid flat above, with broad flat pointed spines around 
its edge ; concave beneath — Euomphalus coronatus. Sower. Min. Conch, t. 
ccccl. f. 3.-~.-Lower Oolite., Ancliff. 
