Ammonita. MOLLUSCA. CEPHALOPODA. 241 



ing in a carinated margin ; aperture cordate. — In limestone of the Upper 

 Oolite, 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 crenated 

 margin ; aperture obtusely square.— Sower. Min. Conch, t. xvii. f. 3. — In a 

 gravel-pit, Suffolk. 



5. A. serrata — Depressed, whorls 5, the inner ones two-thirds concealed ; 

 surface radiated and undulated near the circumference, keel distinct, nearly 

 cylindrical, with a concavity in the shell on each side, sharply crenated, con- 

 taining the siphunculus ; apertures narrow, five-angled. — Sower. Min. Conch. 

 xxiv — At Worlinghame. 



6. A. Mantelli — Depressed, whorls 3 or 4, two-thirds concealed, edge three 

 sided, broad and flattish ; sides flattish, ridges alternately entire, and extend- 

 ing only about two-thirds across the whorl ; the outer edges of the partitions 

 have 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, obtuse 

 ribs, flattened in front ; mouth circular, slightly indented by the preceding 

 whorl — 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 one 

 long 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; ridges 

 broad, slightly curved, tew, and obscure near the margin ; aperture acutely 

 elliptical ; keel sharp — Sower. Min. Conch, t. xcii. f. 4. — In Lias, Char- 

 mouth. 



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 ; aperture 

 longer 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 two- 

 thirds concealed ; 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 large 

 central cavity, ribs numerous, curved, unequal in length, obsolete near the 

 centre ; keel sharp, entire ; aperture acutely triangular, external angle round- 

 ed, internal angles obliquely truncate — Sower. Min. Conch, t. xciv. lowest 

 figure. — Inferior Oolite, Ilminster. A. t. clxvL this species is said to occur 

 likewise 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 alternately 



long and short; aperture long, narrow in front Sower. Min. Conch, t. 103. 



—Chalk Marl, Folkestone. 



15. A. Callovicensis. — Depressed, subumbilicate ; whorls 5, three-fourths con- 

 cealed ; front flat, ribs small, numerous, alternately one long and from two 

 to five short ; aperture orbicular when young, deltoid, with the angles trun- 

 cated when old Sower. Min. Conch, t. 104 Middle Oolite, Kellaways 



Bridge. 



VOL. I. d 



