History of British animals - University of Guam Marine Laboratory

Ammonita. MOLLUSCA. CEPHALOPODA. 241ing in a carinated margin ; aperture— cordate. In limestone of the UpperOolite, at Shotover, Oxfordshire.4. A. quadrala — Depressed, whorls 4 or 5, the inner ones half concealed ;surface with projecting, furcate, undulating radii, extending into a crenatedmargin ; aperture obtusely square.— Sower. Min. Conch, t. xvii. f. 3. — In agravel-pit, Suffolk.5. A. serrata— Depressed, whorls 5, the inner ones two-thirds concealed ;surface radiated and undulated near the circumference, keel distinct, nearlycylindrical, with a concavity in the shell on each side, sharply crenated, containingthe siphunculus ; apertures narrow, five-angled.— Sower. Min. Conch.xxiv—At Worlinghame.6. A. Mantelli— Depressed, whorls 3 or 4, two-thirds concealed, edge threesided, broad and flattish ; sides flattish, ridges alternately entire, and extendingonly about two-thirds across the whorl ; the outer edges of the partitionshave five principal folds ; aperture obscurely six-sided.—Sower. Min. Conch,t. lv—In Chalk Marl, Ringmer, Sussex.7- A .planicosta— Depressed, whorls C, exposed, with transverse, obtuseribs, flattened in front ; mouth circular, slightly indented by the precedingwhorl—Sower. Min. Conch, t. lxxiii.— In Chalk Marl, and Lias?8. A. jugosa.— Depressed, keeled, whorls 4, half concealed, with regular,straight, transverse, obtuse ribs ; aperture ovate, narrowest at the front.—Sower. Min. Conch, f. xcii. f. 1.— In the Inferior Oolite, Ilminster.9. A. triplicata.— Whorls 4, exposed, ribs twice curved, alternately onelong and three short ;a smooth line along the front ;aperture obovate. — Sower.Min. Conch, t. xcii. f. 2.— Upper Oolite, Portland Isle.10. A.elliptica— Depressed, keeled, inner whorls two-thirds exposed; ridgesbroad, slightly curved, tew, and obscure near the margin; aperture acutelyelliptical keel ; sharp —Sower. Min. Conch, t. xcii. f. 4.— In Lias, Charmouth.11. A. stellaris.— Depressed, with a groove on each side of an obtuse keel ;whorls four, flattish on the sides, about two-thirds exposed ribs numerous,;straight, two of which cross each partition syphon in the keel ; ;aperturelonger than wide. Surface with obscure, distant,—decussating strise. Sower.Min. Conch, t. xciii—In Lias at Lime.12. A. elegans — Depressed, acutely keeled, whorls 3, the inner ones twothirdsconcealed ;ribs numerous, equal, twice curved ; keel distinct, entire,aperture acutely triangular, the inner angles truncate. — Sower. Min. Conch,t. xciv. upper figure. — Inferior Oolite, Ilminster.13. A. concava.— Depressed, keeled, whorls 4, two-thirds concealed, a largecentral cavity, ribs numerous, curved, unequal in length, obsolete near thecentre ; keel sharp, entire ; aperture acutely triangular, external angle rounded,internal — angles obliquely truncate—Sower. Min. Conch, t. xciv. lowestfigure. Inferior Oolite, Ilminster. A. t. clxvL this species is said to occurlikewise in the Middle Oolite at Dry Sandford, Berkshire.14. A. splendens Depressed, front flat, with crenulated edges ;whorls 3,quickly diminishing, three-fourths concealed ; sides flat ribs ; alternatelylong and short; aperture long, narrow in front Sower. Min. Conch, t. 103.—Chalk Marl, Folkestone.15. A. Callovicensis.— Depressed, subumbilicate ; whorls 5, three-fourths concealed; front flat, ribs small, numerous, alternately one long and from twoto five short ;aperture orbicular when young, deltoid, with the angles truncatedwhen old Sower. Min. Conch, t. 104 Middle Oolite, KellawaysBridge.VOL. I.d