PLATE VII. 
I, 2. Ammonites Bucklandi. (BucJcland’s Ammonite.) Depressed, with five volutions, inner ones en¬ 
tirely exposed, with large, obtuse ribs, disappearing round back ; back with obtusely rounded carina, on each 
side of which is a sulcus. Diameter, from 1 ft. to 21 in. 
3,5,8. A. Varians. {Variable Ammonite.) Discoidal, compressed, rather thick, sub-umbilicate, carinated ; 
with three or four half-inserted volutions; with transverse, bifurcated, undulated ribs; with six to eight rows 
of rather obtuse tubercles ; carina acute, entire ; aperture sagittate; siphuncle considered external. Umbilicus 
shallow, and sides shallow, bordered by a row of small tubercles, whence ribs emanate and, proceeding obliquely 
across one-fourth of volutions, rise in form of tubercles, and then diverge into two branches, all terminating in 
a tubercle on exterior margin ; keel smooth, prominent, acute ; each margin with series of opposite tubercles. 
Diameter, from 1 in. to 6 in. 
Var. 1, Sub-plana. 8. Volutions depressed, radii linear, inner row of tubercles obscure. External margin 
crenated, keel but slightly elevated, aperture sagittate. 
Var. 2, Intermedia. Volution rather depressed ; ribs broad, well-defined ; tubercles small, distinctly marked; 
external margin tuberculated ; keel prominent; aperture sagittate. 
Var. 3, Tuberculata. Volutions sub-rotund ; ribs short, thick, nodulous; tubercles elongated, very promi¬ 
nent ; carina acute; aperture somewhat rounded. 
4. A. Duncani. ( Duncan’s Ammonite.) Compressed, inner volutions exposed about one-third, with a few 
tubercles upon their sides; whole shell, with many undulating, narrow, oblique ribs, many irregularly furcated, 
somewhat obscure on middle of sides, and terminated on outer extremities by elongated tubercles on terminal 
half of exterior volution, but button-shaped on other half; also a row of tubercles on sides of latter half, towards 
centre of volution; ambit depressed, bounded by two rows of fibuliform tubercles, being a continuation of ribs; 
aperture ovato-sagittate, and equal to about half greatest diameter of shell; sinuated edges of septa sharp, 
distinctly marked. 
6. A. Conybeari. {Conybear's Ammonite.) Compressed, with large, greatly produced, entire keel, on each 
side of which is a concave groove; volutions eight or nine, crossed by numerous, obtuse ribs, being most 
prominent in centre of volutions, and much depressed at the inner sides; inner sides of volutions somewhat 
flattened and slightly angular; aperture oblong-ovate. Size, from 2 in. to 18 in. 
7. A. Planicostatus. {Flat-ribbed Ammonite.) Compressed, with six or eight exposed volutions, crossed by 
many obtuse, nearly straight ribs, widening as they approach the back and depressed near ambit, inclining 
towards aperture ; aperture circular, slightly indented by volutions. 
9. A. Auritus. {Eared Ammonite.) Compressed, with four or five exposed volutions, last one large, occu¬ 
pying about half diameter of shell; surface with depressed, slightly developed, distant, radiating x'ibs, every 
alternate one with a large, obtuse tubercle; exterior margin deeply grooved, with large obtuse, alternating, 
compressed tubercles, projecting in form of ears ; aperture oblong-ovate, slightly sagittate. 
10. A. Splendens. {Splendid Ammonite.) Involute, compressed, with three or four volutions, inner ones 
deeply inserted, outer ones rapidly increasing ; sides flattened, with transverse ribs; a row of distant elongated 
tubercles towards inner margin, from each of which two or three ribs emanate, curving from inner to outer 
margin, where they terminate in angular eminences, forming crenulated margins on sides of carina; dissepi¬ 
ments sinuated, and very foliaceous siphunculus situate near inner margin; aperture oblong, almost equal in 
length to half diameter of shell, and deeply indented by inner volutions. Diameter, ^ in. to 2 in. 
II. A. Binus. {Coupled Ammonite.) Involute, depressed; volutions four; inner ones about two-thirds 
exposed ; ribs radiating in pairs, emanating from round tubercles, situate near inner margin of each volution ; 
turgid, and then bent up towards front, becoming obsolete; keel small, entire; aperture oblong, rectangular, 
one-third diameter of shell, and a little more than one-sixth wide, with rather rounded angles. 
