PLATE IV. 
1. Turrilites Undulata. ( Waved Turrilite.) Vide Plate III. 4, 9. 
2. Ammonites Stellaris. (Star Ammonite.) Involute, with four somewhat depressed whorls; obtusely 
carinated, on each side of which is a rounded furrow, inner whorls about two-thirds visible, with sides flattened, 
producing pentagonal or stellated appearance ; with numerous straight, moderately raised ribs ; whole surface, 
with obscure, decussating strife ; sinuous margin of each septum crossed by two costae ; septa situated at each 
fourth rib; siphuncle placed in keel; aperture quadrangular. Maximum diameter, 4A in. 
B. A. Lewesiensis. (Leices Ammonite.) Depressed; three or four wide, flattened whorls, almost entirely 
concealed, with four or five obscure, radiating ridges ; septa sinuous, very numerous ; surface, usually with thin, 
foliaceous impressions; external whorl equal to four-sevenths of diameter of shell; umbilicus minute; carene 
very narrow, rounded; aperture sagittate. Maximum diameter about 14 in.; width of outer whorl, 9 in. ; 
maximum thickness, 5 in.; at external edge, 11 in. 
4, 9, A. Mantelli. (MantelVs Ammonite.) Discoidal, depressed, sub-umbilicate; whorls three or four, sub¬ 
rotund, about two-thirds concealed; margin trigonal; with numerous, transverse, tuberculate ribs, alternately 
reaching entirely round whorls; from two to eight rows of tubercles; ambit flattish, with two rows of marginal 
tubercles; external edges of septa with five principal folds; aperture nearly hexagonal, outside embracing 
adjoining whorl; septa numerous, very foliaceous. 
Figs. 4, 9, one of three varieties ; viz. A. Mantelli Costata. 
5, Base of Turrilites tuberculata ; vide Plate III. 5. 
6, 6. A. Striatus. (Striated Ammonite.) Discoidal; very gibbose; inner whorls entirely concealed ; outer 
surface obscurely undulated transversely, with numerous, fine, concentric striae; aperture semicircular, with 
nearly parallel margins; septa zigzag, rather remote, with four angular folds; siphuncle placed at external 
margin of septum; shell very thin. Dorsal lobe bifid; dorsal sinus and first lateral lobe acute; second lateral 
lobe obtusely rounded ; marginal sinus angular ; siphuncle not continuous. 
7,7. A. Sphaerieus. (Spherical Ammonite.) Orbicular; diameter and thickness nearly equal; inner 
volutions entirely concealed ; outer surface, with very fine, spiral striae ; septa, with four broad, angular folds ; 
lateral lobe less acute than in preceding species. 
This grows to double the size of A. Striatus. 
8. A. Obtusus. (Obtuse Ammonite.) Vide also Plate VI. 4. Discoidal; with obtusely rounded and elevated 
keel; slight sulcus on each side ; six volutions, inuer ones wholly exposed, with large curved, remote, slightly 
elevated, strong ribs; aperture oblong, longer than wide, about equal to one-third of diameter. Largest 
diameter, 5-i in. 
9. Vide Fig. 4. 
10. A. Minutus. (Minute Ammonite.) Orbicular, with small umbilicus; thickness and diameter nearly 
equal; inner volutions concealed, with numerous, concentric, wide striae, about 24 in number; aperture semi¬ 
lunar. Diameter, \ in. 
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