History of British animals - University of Guam Marine Laboratory

:314 MOLLUSCA. PECTINIBRANCHIA. Skenea.266. S. divisa.— Whorls three or four ; the upper half ofeach smooth, the under half spirallystriated.Turbo divisus, Adams, Linn. Trans, iii.254.—Common from deep water.Breadth scarcely a line ; white, glossy, subpellucid whorls ; round, nearlyon a level above, with a deep separating line ; beneath, the central cavity islarge, and exposes the superior volutions; aperture circular, and usually detachedfrom the body -whorl.The following Extinct Species appear to belong to this genus.1. S. cequalis— Equilaterally concave, with one obscure keel on the rightside, and two on the left ; smooth ; whorls orbicular.—exposed ; apertureSower. Min. Conch, t. cxl. f. 1.— In Carboniferous Limestone.2. S. concava.— Discoid, involute, flat on one side, concave on the other ;whorls four, the last but slightly attached—Vermicularia con. Sower. Min.Conch, t. lvii. f. 1-5. —In Green Sand.3. S. umbonata Discoid, involute ; umbonated above, concave beneath ;whorls three, the smallest concealed in the umbo—Vermicularia umb. Sower.Min. Conch, t. lvii. f. G, 7—Mr Mantell adds, that the outer volution is produced,and marked with distant annular ridges.— Geo]. Suss. iii. t. xviii. f.24 Grey Chalk Marl.4. S. ovata Discoid, involute, rudely ovate, a little concave beneath ;whorls three.— Vermicularia ovata, Sower. Min. Conch, t. lvii. f. 8 UpperOolite.5. S. catillus Depressed ; beneath nearly flat, above concave, somewhatcontracted, crossed with oblique striae ; whorls three, externally broad, convex,oblique, transversely striated, and bordered on each side by a sharp edge.Helix catillus, Mart. Derb. t. vii. f. 1, 2— Euomphalus cat. Sower. Min.Conch, t. xlv. f. 3, 4—In Carboniferous Limestone.6. S. perangulatus.—A prominent central ridge or rising angle on the upperside, within which is a flat obliquely depressed space to the separatingline ;the other side obtusely angulated ; striae of hair-like growth whorls;almost wholly exposed ; aperture obscurely pentangular, rounded on the outerside Park. Org. Rem. — iii. 77- t. vi. f. 7, 8. Euomphalus pent. Sower. Min.Conch, t. xlv. f. 1, 2 Carboniferous Limestone, Ireland.— 7. S.funata. Conical, very short; with many spiral threads, united bymore numerous transverse lines ; central cavity rather small Euomphalusfun. Sower. Min. Conch, t. ccccl. £ 1, 2— Carboniferous Limestone, Dudley.8. S. carinata Discoid, smooth, whorls five ventricose, obtusely carinated;convex below, central cavity large; aperture transverse, obovate.—Cirus car. Soiver. Min. Conch, t. ccccxxix. f. 3, 4— Lias, Cheltenham.Gen.EUOMPHALUS— Spire produced.1. E. acutus Whorls eight, conical, sharp, with an obtuse ridge near theupper part of each, within which there is a —flat space ; aperture round.Sower Min. Conch, t. cxli.— In Carboniferous Limestone, Ireland—It is nearlyrelated to Skenea pentangularis, from which it differs in the producedspire, and in the Hat space on the top of each whorl not reaching to thecentre.2. E. rotundatus Conical, nearly smooth, whorls convex ; central cavitylarge ; aperture round. — Cirus rotundatus, Sower. Min. Conch, t. ccccxxix. fI, 2.—Carbo7iiferous Limestone, Yorkshire.