402 



THE LIAS AMMONITES. 



rounded and slightly crenated by stria3 ; aperture triangular or slightly ovate. Found in 

 the ironstone bands of the Middle Lias along with A. Hauiskerensis." 



Affinities and Differences. — This species very much resembles Amal. margaritatus, of 

 vi^hich it may be only a variety of that well-defined form. Those naturalists who insist upon 

 the distinctness of the two species point to the longitudinal ribbing of the shell, the larger 

 amount of the involution of the whorls, and smallness of the umbilicus in Amal. Engelhardti, 

 the more complicated convolutions of the suture-line and the minute subdivisons of the 

 lobes and saddles, and likewise the fact that the same characters are persistent throughout 

 its life-history which approximate to, but are distinct from, some of the more lenticular 

 varieties of Amal. margaritatus. 



Locality and Stratigraphical Position. — This Ammonite has been collected from the 

 upper portion of the Marlstone beds of the Middle Lias at Grettan Hill, near Winchcombe, 

 and at Stinchcombe Hill by Dursley, localities which have yielded all the fine specimens 

 I have obtained in Gloucestershire. It is found in the same bed at Yeovil, South 

 Petherton, and Ilminster, Somersetshire, along with Amal. spinatus. In Yorkshire it is 

 collected from the Amal. spinatus-zone, in the rich ironstone beds at Eston, Upleatham, 

 Hawsker, &c., so that its true horizon is the uppermost strata of the Middle Lias. 



Amaltheus spinatus, Bruguiere. PI. LV, figs. 1 and 2 ; PL LVI, figs. 1 — 5. 



Ammonis CORNU, Lachmund. Oryctogr. Hildesheim, p. 49, 1669. 



— — Lister. Hist. Animal. Anglise, p. 207, tab. vi, fig. 3, 16/8. 

 _ — — Synops. Conchyl., Edit, alt., tab. 1041, fig. 21, 



1770. 



— — Baier. Oryctographianorica, p. 64, tab.3,fig8. 4, 5, 1708. 



— — Leibnitz. Protogsea, p. 41, tab. 5, 1749. 



— — Knorr and Walch. Petrif., torn, ii, t. a II, fig. 1, 1755. 

 Bruguiere. Encycl. Method., t. i, p. 40, No. 14, 1792, 

 Bosc. Bufibn de Deterville, t. v, p. 1/6, 1801. 

 Roissy. Hist, des Mollusques, t. v, p. 25, 1805. 

 Reinecke. Naut. et Argon., p. 87, tab. i.\, figs. 68, 69, 



1818. 

 Schlotheim. Die Petrefaktenkunde, p. 70, No. 16, 1820. 



— Ibid., p. 68, No. 12, 1820. 



Haan. Mon. Amm. et Goniatites, p. 102, No. 1, 1825. 



Geol. Survey, p. 258, pi. xiv, fig. 6, 

 1828. 

 Geol. of Yorkshire, pi. xiii, fig. 8, 1829. 



— COSTATUS, Zieten. Versteiner. Wiirtemb., p. 5, pi. iv, fig. 7, 1830. 

 _ _ Roemer. Norddeut. Oolithengebirg.,p. 188, No. 16, 1836. 



— — Bronw. Leth.geognostica, Bd.i, p. 436, t. xxii, fig. 12, 1837 



Ammonites spinata, 



Nautilus costatus. 



Ammonites angulatus, 

 — costatus, 



Hawskerensis, Young and Bird. 

 — Phillips. 



