AMALTHEUS MARGARITATUS. 



397 



Amaltheus MARGARITATUS, Monf/ort. Pis. LIII, LIV, figs. 1 — 3, and LVI, figs. 6 — 



16, 19, 20. 



Ammonis cornu steiatum striis BA.R10EIBUS, Langius. Hist. Lapid. Figuratorum Hel- 



vetise, p. 96, tab. xxv, fig. 2, 1/08. 

 iSeba. Thes., vol. iv, tab. 107, figs. 6, 10, 13, 



1734. 

 Knorr et IValch. Tome II, p. 42, pi. a li, fig. 3, 1768. 

 Montfort. Conchyliologie Systematique, t. i, p. 90, 



fig. xxiii, 1808. 

 Sowerhy. Mineral Conchology, vol. i, p. 51, pi. 17, 



fig. 1, 1813. 

 Reinecke. Nautili et Argonautse, No. 5, p. 59, 



tab. i, figs. 9, 10, 1818. 

 Sowerby. Mineral Conchology, vol. ii, p. 205, 



tab. 191, 1818. 

 Schlotheim. Die Petrefactenkunde, p. 66, No 9, 

 1820. 

 — GiBBOSus — Ibid., No. 10, p. 66. 



Clevelandicus, Young and Bird. Geol. Surv. Yorksh. Coast, p. 253, 



pi. 13, fig. 11, 1822. 

 Haan. Amnion, et Goniat., p. 106, 1825. 



— Ibid., p. 108, 1825. 



— Ibid., p. 105, 1825. 

 Phillips. Geology of Yorkshire, pi. xiv, fig. 6, 



1829. 

 Zieten. Versteinerungen Wiirttembergs, p. 4, pi. 4, 

 fig. 1, 1830. 



— — GIBBOSUS, — Ibid., pi. 4, fig. 2. 



PARADOXUS, — p. 15, pi. xi, fig. 6. 



— AMALTHEUS, Roemer. Norddeutsch. Oolithen-Gebirg., p. 188, 



1836. 



— — Bronn. Lethsea geog., p. 434, pl.xxii, fig. 13, 1837. 

 Amaltheus MARGARITATUS, Tate and Blake. Yorkshire Lias, p. 293, 1876. 



Diagnosis. — Shell discoidal, much compressed ; whorls one half involute, outer whorl 

 flattened on the sides, slightly convex and transversely costated ; costse in form of doubly 

 bent convex folds, the outer curve inclined forwards towards the aperture ; siphonal area 

 narrow and carinated ; keel formed of short supplemental ribs, which grasp the margin 

 of the whorl and have their angles directed forward, forming a rope-like structure 

 extended along the outer margin ; the external half of the whorls covered with close-set 

 longitudinal lines ; aperture narrow, compressed, and sagittate; lobe-line highly com- 

 plicated. 



CoRNU Ammonis, 



Ammonite, 



Amaltheus margaritatus. 



Ammonites acutus. 

 Nautilus rotula. 

 Ammonites Stokesi, 

 — amaltheus, 



rotula, 

 acutus, 



amaltheus, 

 Clevelandicus, 



amaltheus. 



