172 



that coast. In Gloucestershii-e I have collected small ribbed specimens 

 from the lowest shades of the Fretherue section on the banks of the 

 Severn, and it has likewise been found at Aust Cliff. In Warwickshii-e 

 some fine specimens were obtained from the Harbury cutting of the 

 Great Western Railway, near Southam, and many good fragments are 

 still to be found on the spoil banks of that line. In Yorkshire it is 

 found only in the lowest beds of Lias at Redcar, where it is very rare, 

 and known to local collectors as A. Redcarensis. It is found in the 

 same zone of Lower Lias near Portrush, on the north-coast of Ireland. 



The varieties of this species figured by d'OiiBiGNY were collected in 

 France from the lowest beds of the Lias with Gryphcea incurva, Sow. ; 

 at Pont-Auber, near Avail on, (Yonne,) and Champlong, near Semur, 

 (Cote-d'Or.;) at Jamoigne, (Luxembourg,) and in several places in Germany 

 near Balingen, Degerloch, Stuttgard, and other localities. It everywhere 

 characterizes beds which are interposed between the Planorbis and 

 Bucklandi series. 



Ammonites Bucklandi, Soiverby. (PL 1, fig. 2, a, h.) 

 Ammonis cornu. Lister, Conchili Anglise, tab. 6, p. 207, 1678. 

 Ammonis cornu striatum, Lang, Historia Lap., Fig. Helvetise, tab. 24, 



p. 95, 1708. 

 Ammonites bisulcata, Brugui^re, Encyclopedic M^thodique, tom. 1., 



p. 39, 1792. 

 Ammonites Bucklandi, Sowerhy, Min. Couch., tab. 130, p. 69, vol.2, 1816. 

 ,, M V. Bucli, Berlin Akad, tab. 3, fig. 1. 1830. 



„ M Zieten, Petrif. Wurtemb.,tab. 27,fig. 1, p. 35, 1830. 



Shell discoidal, depressed ; whorls slightly involute ; sides convex and 

 largely costated; ribs thick, bent, remote, 24 in a whorl; back flat, 

 strongly carinated, with a deep furrow on each side of the keel; aperture 

 quadrato-hemispherical. 



Dimensio7is. — Transverse diameter 9 inches; height of the whorl at 

 the aperture 2| inches ; width 3 inches ; whorls about one-fifth involute. 

 Many of the lai'ge specimens from Keynsham and Lyme Regis measure 

 18 inches in diameter. 



Description. — ^This Ammonite attains a gigantic size, it has a flattened 

 discoidal shell, formed of six or seven slightly involute whorls, having 

 the inner ones largely exposed; the sides are convex, sub-cylindrical, and 

 separated by a deep suture, having strong prominent libs, about 24 in 

 a whorl, which are rounded, distant, simple, arched, and terminate 

 abruptly on the dorsal border where they are interrupted ; the back 

 forms a broad flattened arch, and the middle line is occupied by a sti-ong 



