PLATE XIII. 
1. Ammonites Funiferus. ( Corded Ammonite.) Lenticular, deeply umbilicate, carinated, thick 
in centre, thin at external margins; obscurely ribbed transversely, with stronger grooves passing 
over thinly carinated back ; inner volutions concealed ; aperture acutely sagittate, much compressed, 
nearly equal in length to half diameter of shell. Greatest diameter, 4 in. 
2. 11. A. Ptychomphalus. ( Plaited-umbilicus Ammonite.) Discoidal, largely umbilicate, 
around which from eight to ten divergent, wide, somewhat acute protuberances; ambit rounded, 
plain ; aperture ovate. Greatest diameter, 5£ in. Fig. 2 represents adult fossil; fig. 11 the young. 
3. A. Lenticularis. ( Lens-shaped Ammonite.) Lenticular, smooth, inner volutions concealed, 
umbilicate, with plain, slightly rounded keel; aperture sagittate, equal to nearly half diameter of 
shell; thickened in centre and sloping off towards thin, smoothly carinated ambit. 
4. A. Catinus. ( Chain Ammonite.) Depressed, with from six to eight smooth volutions, with 
flattened sides, inner ones exposed, with two series of short, blunt, fairly large, conical, round, pointed 
tubercles on each side of interior and exterior angles of volutions; ambit slightly convex; aperture 
quadrangular; margins of septa sharp, deeply sinuated. Largest diameter cir. 13 in. 
5. A. Parkinsoni. ( Parkinson’s Ammonite.) Discoidal, with seven to nine slightly convex 
volutions; inner ones exposed; crossed by many elevated, arcuated ribs, bent forward at exterior 
ends, furcated near ambit; ambit narrow, plain; aperture oblong, narrowed towards back. Greatest 
diameter, 18 in. 
6. A. Solaris. ( Sun Ammonite.) Discoidal, carinated, with four flatfish volutions, inner ones 
exposed, with numerous elevated, smooth ribs, reaching entirely across volutions; keel acutely 
triangular; aperture spatuliform, acute next to ambit. 
7,9. A. Mutabilis. {Mutable Ammonite.) Compressed, with four or five smooth volutions; 
inner ones two-thirds exposed, showing tuberculated, wide-set ribs ; ambit rounded ; aperture ovato- 
sagittate. Largest diameter, 10 in.; thickness of external volutions, in. Fig. 9 represents shell 
in young state. 
8. A. Oculatus. {Eyed Ammonite.) Compressed, slightly depressed; umbilicate; inner volutions 
hidden, with many, depressed undulating ribs from margin of umbilicus to near ambit, where is a 
series of remote, nearly circular, depressed tubercles; with series of close-set oblong tubercles on both 
sides of smooth ambit. 
10. A. Athleta. {Champion Ammonite.) Shell strong, with six volutions, inner ones almost 
wholly exposed; sides, crossed by numerous, strong, elevated ribs, with oblong, produced tubercle at 
each end; each dividing into three narrow, exserted, smooth ribs on flattened, square ambit, uniting 
with tubercles on opposite side; inner volutions gradually diminish in thickness near centre, whole 
side forming widely reversed cone ; aperture nearly quadrangular. 
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