PLATE VIII. 
1. Ammonites Lautus. ( Laurel Ammonite.) Discoidal, involute, compressed, with three or four two-thirds 
inserted volutions; back narrow, deeply channelled sides, with many strongly arcuated, slender ribs, in pairs 
from a row of oblique, elongated tubercles near inner margin, and being joined by alternating intermediate 
shorter ones, proceed in a curve to outer margin, where they terminate in rather depressed, large, alternating 
tubercles; edges, serrato-tuberculate; dissepiments very foliaceous ; aperture obscurely sagittate, equal to half 
diameter of shell. 
2. A. Armatus. ( Armed Ammonite.) Involute, with six or seven exposed volutions pressed against each 
other, and crossed by many annular ribs, each with two series of large short, furrowed spines, five on each ; 
costae, after meeting in point of spines, continue on the other side; aperture obscurely four-sided; siphuncle 
situate near dorsal margin of aperture. 
3. A. Planus. (Flat Ammonite.) Involute, carinated, compressed, deeply inserted, almost smooth; volu¬ 
tions crossed by nearly obsolete striae ; keel flat, with margin crenulated; aperture sagittate; dissepiments 
sinuate. 
4. A. Cordatus. (Cordate Ammonite.) Involute, carinated; volutions, four or five, somewhat compressed, 
inner ones half inserted ; sides, with undulating ribs, extending over inner half of each volution; remaining 
half, with about five divergent undulations to every two ribs, all terminating in exterior crenated margin ; 
aperture cordiform, two-thirds of diameter of shell in length. Diameter, 1 to 2 in.; thickness about one- 
third of diameter. 
5. A. Browni. (Brown's Ammonite.) Discoidal, carinated; five half-inserted volutions, with a zone ot 
large, distant tubercles situate towards centre of the volutions, rather nearer inner side ; from tubercles the 
other half of the volutions, with numerous equidistant, curving ribs, extending over rounded ambit; aperture 
cordiform. 
6. A. Annulatus. (Ringed Ammonite.) Discoidal, with five to seven exposed volutions, crossed by many 
close, prominent ribs, frequently bifurcated on passing over rounded ambit; aperture cordiform. 
7. A. Curvatus. (Rending Ammonite.) Also Plate X. fig. 12. Discoidal, carinated, compressed, sub- 
umbilicate, with three deeply inserted volutions, with numerous transverse, falciform ribs, bifurcated at com¬ 
mencement, and terminating in broad, curved, tubercular costas; keel, with longitudinal sulcus, situated between 
two marginal series of tubercles ; ambit flat, narrow ; umbilicus large ; aperture obtusely sagittate ; siphunculus 
situated in dorsal sulcus. 
8. A. Falcatus. (TTooked-Ribbed Ammonite.) Discoidal, carinated, greatty compressed, sub-umbilicate, with 
three deeply inserted volutions, flat on both edges; sides, with numerous close, plicated, falciform ribs, extending 
a little way down the sides of small umbilicus ; ambit flat, narrow, with longitudinal sulcus; margin plicated ; 
aperture sagittate; siphunculus placed in sulcus. 
9. A. Brocchii. (Brocchi's Ammonite.) Compressed, with three or four great rounded volutions ; inner ones 
half concealed; sides hollow ; ambit circular, with a row of oblong-ovate ribs near inner margin of volutions 
extending nearly to centre, where they meet numerous obtuse, arcuated ribs, passing over round ambit; aperture 
semi-lunar; thickness half diameter of shell; septa very numerous and beautifully sinuated. Greatest diameter B in. 
10. A. Serratus. (Serrated Ammonite.) Discoidal, involute, compressed, carinated, with five volutions, 
two-thirds inserted, with distant, strong, arcuated ribs extending from ambit to nearly centre of volutions ; many 
curved costae emanate from inner margins of volutions and nearly meet others in centre ; sides of volutions some¬ 
what concave, contiguous to cylindrical keel, with sharp crenulations and containing siphunculus ; aperture nar¬ 
row, pentangular, extending to half diameter of shell; septa close, with numerous deep undulations. Largest 
diameter 4 in., thickness 1 in. 
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