312 MOLLUSC A. PECTIN IBRANCHI A. Scalaria. 



most prominent. Ribs 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. semicostala. — AVhorls about 1, contiguous ; spire transversely striated, 

 ribs numerous, but slightly raised, lower part of each volution smooth, naked. 

 — Sower. Min. Conch, t. xvi. middle figure. — In London Clay, from Barton 

 Cliff, and in Crag of Suffolk, (lb. t. 390.') 



3. S. acuta. — Whorls about 1, rather distant ; spire with three slight trans, 

 verse risings, and a fourth very prominent one, near the lower part of each 

 turn, llibbs 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. snbulata. — Whorls contiguous; ribs 10 or 12, thick, reflected; the in- 

 tervening spaces smooth— Sower. Min. Conch, t. cccxc. f. 1 — Crag, Suffolk. 



5. S.foliacea. — 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. — 

 Soiver. Min. Conch, t. cccxc. f. 3, 4.— Crag, Suffolk. 



Gen. LIII. CYCLOSTREMA — Spire short; transverse 

 ridges on the body-whorl disjoined from the pillar by a 

 crenulated groove. 



262. 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 ; white ; 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. — Whorls 4, the upper ones depressed, farm- 

 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. D. coronata Discoid flat above, with broad flat pointed spines around 



its edge ; concave beneath — Euomphalus coronatus, Soiver. Min. Conch, t. 

 ccccl. f. 3.— Lower Oolite, AnclifK 



