312 MOLLUSC A. PECTINIBRANCHIA. Scalahia. 



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. 

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

 Cliff, and in Crag of Suffolk, (76. t. 390.') 



3. S. acuta. — "Whorls about 7, rather distant ; spire with three slight trans- 

 \'erse risings, and a fourth very prominent one, near the lower part of each 

 turn. Ribbs 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. 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. — 

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



Gen. LIIL 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. DELPHTNULA.— Spire depressed, produced, 

 and tuberculated. 



263. D. calcar. — Whorls 4, the upper ones depressed, form- 

 ing a flat summit. 



Mont. Test. Brit. Sup. 137, t. xxix. f. 3 — On the shore of lona, Mr 

 Laskey. 

 Breadth about a quarter of an inch ; of a pale pink colour ; round ; on the 

 body and part of the second whorls arc large, smooth, lanceolate spines, ra- 

 diating in straight lines fi-om the shell, about 13 in number ; base convex, 

 with a central cavity ; aperture orbicular. 



EXTINCT SPECIES. 



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



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



ccccl. f. 3.— Lower Oolite, Ancliff. 



