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 

 rae 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 M. Kaza- 

 nensis, and from the neighbourhood of Kazan ? 



Monotis radialis, Phillips. Plate XIII, figs. 22, 23. 



(?) Pecten, sp. 2, (S. N.), J. de C. Sow. Trans. Geol. Soc. Lond., 2d series, vol. iii, 



p. 120, 1829. 

 Pecten radialts, Phillips. Encyc. Met., vol. iv, pi. iii, 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; and a 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 striae, slightly tuberculated ; about the same 

 size as" Pecten pusillus ; which is perhaps a hurriedly drawn-up description, as the 

 specimen figured in the ' Encyclopaedia Metropolitana' is much larger, and clearly 

 the present species. 



Monotis radialis occurred to Professor Phillips in the Shell-limestone of Humbleton, 

 which is the only locality for it kno\NTi to me. 



Monotis Garforthensis, King. Plate XIII, fig. 24 and (?) fig. 25. 



Diagnosis. — Upper valve moderately convex ; with numerous fine radiating tubu- 

 liferous ribs, and a moderate-sized umbone. 



