Ammonita. MOLLUSCA. CEPHALOPODA. 245 



keel broad, obscure, crenulated within. — Sower. Min. Conch, t. xcii. f. 5.— In 

 clay, Middle Oolite, Scarborough. 



58. A. Una. — Depressed, keeled, whorls 4, the inner ones two-thirds ex- 

 posed ; ribs diverging in pairs from round tubercles, swelling and then turn- 

 ing up towards the front, and disappearing ; aperture oblong rectangular, the 

 angles rounded. — Sower. Min. Conch, t. xcii. f. 3 — Plastic Clay, Bramerton 

 Norfolk. 



59. A. armata. — Whorls 6, exposed, with many annular undulations, arm- 

 ed with two rows of large conical short furrowed spines ; aperture obscurely 

 four sided — Sower. Min. Conch, t. xcv In Lias, Whitby. 



60. A. monilis.— Whorls 4, exposed, subumbilicate, the outer margin rather 

 depressed ; ribs tuberculated, striated ; aperture transversely ovate. — Sower. 

 Min. Conch, t. cxvii. — Green Sand, Folkstone. 



61. A. aurita — Depressed, whorls 5, exposed, with obscure radiating un- 

 dulations, tuberculated at their origin ; back deeply channelled, bordered by 

 large alternating compressed tubercles. — Sower. Min. Conch, t. cxxxiv. — In 

 Green Sand. 



62. A. Duncani — Depressed, inner whorls partly exposed ; edge flat, bound- 

 ed by two rows of tubercles ; ribs numerous, undulated, irregularly furcate ; 



aperture ovato-sagittate Sower. Min. Conch, t. clvii In the clay of the 



Middle Oolite. 



63. A. vertelralis — Whorls 4, inner ones partly concealed, carinated ; ribs 

 numerous, prominent, tuberculate in the middle, then furcate, with a tuber- 

 cle on each branch ; keel serrato-tuberculate ; aperture orbiculate Sower. 



Min. Conch, t. clxv — In Middle Oolite, near Abingdon, Berkshire. 



64. A. Henleyi — Whorls few, increasing rapidly, the inner ones exposed ; 

 ribs numerous, with two compressed tubercles upon each ; the ribs usually 

 divided from the outer tubercle ; aperture large, slightly round. — Sower. Min. 

 Conch, t. clxxiii. — In Lias, Dorsetshire. 



65. A. rostrata — Shell depressed, carinated ; whorls 4, exposed ; ribs large, 

 obtuse, with three or four tubercles, largest in front ; aperture elliptical, with 

 a compressed reflected beak — Sower. Min. Conch, t. clxxiii — In Chalk Marl, 

 Oxfordshire. 



66. A. varians — Depressed, carinated, whorls 3, half exposed; a row of 

 large tubercles near the front, and one or two rows of lesser tubercles placed 

 upon furcate radiating undulations — Sower. Min. Conch, t. clxxvi. — In Chalk 

 Marl. 



67- A. i/i./?«ta.— Depressed, inner whorls exposed, carinated, sides and front 

 flattish ; ribs commencing with a compressed tubercle, then furcate ; keel 

 distinct ; aperture square. — Sower. Min. Conch, t. clxxviii — In Green Sand, 

 Isle of Wight. 



68. A. rustica. — Depressed ; whorls 3 ; gibbose, exposed, with 6 or 8 conical 

 tubercles upon the sides of each, and two rows of obtuse tubercles around the 

 front, which is flat ; aperture quadrangular. — Sower. Min. Conch, t. clxxvii. 

 — In the Lower Chalk, near Lyme. 



69. A. Banksii Whorls 5, exposed, sides concave, largely tuberculated ; 



front fluted, slightly convex ; aperture transverse, almost three times as long- 

 as wide — Soiver. Min. Conch, t. cc Under Oolite. 



70. A. Blagdeni. — Subcylindrical, obtusely fluted, umbilicate; umbilicus 

 reaching to the margin, conical, with large radii, terminating upon the edge 



