ANIMALS. 157 
Schlotheim, who gave some excellent representations of it in the ‘ Denkschriften der 
Koniglichen Akademie zu Miinchen,’ was the first to make it known, as occurring at 
Gliicksbrunn. ‘Dr. Geinitz notices its being found in the lower Zechstein of Corbusen ; 
in the upper Zechstein at Roschiitz; and in the Zechstein-dolomite of Possneck, Konitz, 
Altenstein, &c. In England it is found in the Shell-limestone of Humbleton Quarry, 
Ryhope Field-house Farm, Dalton-le-Dale, Tunstall Hill, Silksworth, Hylton North Farm, 
north end of Black Hall rocks, and Castle Eden Dene. A few examples occurred to 
me in the breccia of Tynemouth Cliff; and a single specimen in the fragment of 
Magnesian Limestone dredged up near the Dogger Bank. M. de Verneuil and Count 
Keyserling notice specimens found in the Russian Permian rocks near Arzamas, 
and of Ust-Joschuga, apparently belonging to this species. Is the flat valve, already 
noticed, as resembling Monotis speluncaria, from the same deposit containing J. Kaza- 
nensis, and from the neighbourhood of Kazan ? 
Monotis rAp1aALis, Phillips. Plate XIII, figs. 22, 23. 
(?) Pectzn, sp. 2, (S. N.), J. de C. Sow. Trans. Geol. Soc. Lond., 2d series, vol. iii, 
p. 120, 1829. 
PECTEN RADIALIS, Phillips. Encye. Met., vol. iv, pl. ili, fig. 5, 1834. 
Monotis — = King, Catalogue, p. 9, 1848. 
Diagnosis.—Somewhat elliptical longitudinally in its marginal outline; with a short, 
straight, hinge-line. Large valve with numerous, fine, radiating, slightly tuberculated 
ribs; anda very small umbone. Small valve (unknown). 
This species might be taken for a flattened variety of Monotis speluncaria, a view 
which I am certainly not prepared to urge any strong objection against ; but it differs 
therefrom in having a very slightly developed umbone, and in being a narrower and 
longer shell. It varies equally as much as the latter in its marginal outline and 
superficial ornamentation (vide Pl. XIII, figs. 22, 23). Professor Phillips describes it 
as being “ convex, circular, marked with striz, slightly tuberculated; about the same 
size as” Pecten pusillus; which is perhaps a hurriedly drawn-up description, as the 
specimen figured in the ‘ Encyclopedia Metropolitana’ is much larger, and clearly 
the present species. 
Monotis radiahs occurred to Professor Phillips in the Shell-limestone of Humbleton, 
which is the only locality for it known to me. 
Monotis GARFORTHENS!1S, Aiug. Plate XIII, fig. 24 and (?) fig. 25. 
Dagnosis.—Upper valve moderately convex; with numerous fine radiating tubu- 
liferous ribs, and a moderate-sized umbone. 
