Ammonita. MOLLUSCA. CEPHALOPODA. 247 



83. A. fibulata. — Depressed, ribbed 4 inner whorls almost wholly exposed, 

 sides of the whorls flattened, their inner margins plain ; ribs numerous, unit- 

 ed in pairs by smooth solid spines. — Soiver. Min. Conch, t. ccccvi. f. 2. — In 

 Luis at Whitby. 



84. A. catena. — Depressed, furnished with two rows of short tubercles up- 

 on each side ; whorls 6 or 8, smooth, with flat sides, the inner ones exposed ; 

 front rather convex; aperture square. — Sower. Min. Conch, t. ccccxx. — 

 Middle Oolite, near Abingdon, Berkshu'e. 



85. A. cmtote.— Lenticular flattened ; carinated ; keel thin, deeply notch- 

 ed; inner whorls concealed — Sower. Min. Conch, t. ccccxxi. f, 3. — Middle 

 Oolite, Weymouth. 



86. A. Johnstoni — Discoid ; whorls G or 8, two-thirds exposed, with nu- 

 merous short straight costte upon the exposed parts ; front Tplain.—Sozver. 

 Min. Conch, t. ccccxlix. f. i. — In Lias at Watchet. 



87. A. varicosa Depressed, costated ; inner volutions exposed ; carinated 



when young, and furnished with an in'egular row of tubercles u])on the in- 

 ner edges of the whorls ; costae curved, large, obtuse, in old shells crossing 

 the fi-'ont ; carina distinct ; aperture oblong. — Sower. Min. Conch, t. ccccli. f. 

 4, 5. — Sandstone, Blackdown. 



88. A. rotiformis. — Depressed, ribbed, carinated, a furrow upon each side of 

 the keel; inner whorls exposed, many ; ribs many, strong, each terminating 

 in a tubercle ; aperture nearly square. — Sower. Min. Conch, t. cccclui. 



89. A. mtdticostata. — Depressed, costated, carinated, a furrow on each side of 

 the keel ; inner whorls exposed, few ; ribs strong, sharp, numerous, with a 

 tubercle near the end of each ; aperture oblong, — Sower. Min. Conch, t. ccccliv. 

 — In Lias, near Bath. 



90. A. Humphriesiana.— Discoid, thick, radiated; inner whorls exposed ; front 

 rounded ; radii large, numerous, rising into a tubercle on each side the Avhorl, 

 where they branch into three ; aperture arched, oblong. Soivcr. Min. Conch. 

 t. D. f. I. — Inferior Oolite, Sherborne. 



91. A. contractu. — Subglobose, umbilicated, radiated ; radii rising into tuber- 

 cles upon the border of the umbilicus, there dividing into three or four branches 

 that pass over the much rounded front ; aperture oblong, arched ; inner whorls 

 almost concealed — Sower. Min. Conch, d. f. 2. Dimdry. 



92. A. Listeri. — Subdiscoid ; inner whorls partly concealed ; front convex, 

 broad, crossed by nvunerous small ribs ; sides inversely conical, ribbed ; ribs 

 terminated by tubercles.— Mart. Pet. Derb. t. xxxv. £ 3. — Soioer. Min. Conch. 

 Di. f. I.— Carbonifercms Limestone. 



93. A. longispina. — Discoid, thick, with two concentric rows of spines upon 

 each side ; whorls few, half exposed ; front roimd. — Soever. ]VIin. Conch, t. di. 

 f. 2. — Weymouth. 



94. ^. Tayori.— Discoid, radiated ; inner whorl exposed; radii about 12,'with 

 one large spiniform tubercle upon each side of the front, and one or two slight 

 elevations on the rounded sides of the whorls ; aperture nearly round — Sower. 

 Min. Conch, t. D. xiv. f. 1 In clay, Happishurg Cliff. 



95. A. hippocastanum — Gibbose, umbilicated, radiated, spinose ; inner whorls 

 almost concealed ; radii ten or more, unequal, much elevated, each furnished 

 with three tubercles upon the front, and most of them with two obtuse spines 

 upon each side; aperture transversely ovate.— (S'orce?-. Min. Conch, t. Dxiv. 

 il 2 — In chalk, Dowlands. 



