AVICULOPECTBN CARROLLI. 97 



the posterior ear are made rugose by striae of growth near tlie junction with the 

 valve, but this portion of the valve in P. Bouei is smooth," and he says there is a 

 difference in the number of thin radiating ribs intercalated between the principal 

 ones, but is not more explicit on the matter. I have followed Eichwald, and 

 consider the specific names as synonyms. 



Aviculopecten Ruthveni, M'Coy, sp., 1851. Plate XIV, fig. 22. 



AvicuLorECTEN Ruthveni, M'Coy, 1851.- Ann. Mag. Nat. Hist., ser. 2, vol. vii, 



p. 172. 

 — 1855. Brit, Pal. Foss., p. 489, pi. 3 e, fig. 4. 



Pecten granosus, Boemer, 187G. Lethaea Geogn., Atlas, taf. xliv, fig. 4. 



Aviculopecten Ruthveni, de Koninck, 1885. Ann. Mns. Roy. d'Hist. Nat. Belg., 



torn, xi, p. 213, pi. xxxvii, figs. 7, 10, 

 11; pi. xxxviii, figs. 17, 18. 



Specific Characters. — Shell of medium size, suborbicular, moderately convex. 

 Ears large and depressed, hinge-line straight, of moderate length. 



Inferior. — Unknown. 



Exterior. — Surface with about twelve thick, rugged, radiating ribs, between each 

 pair of which are usually three smaller ribs. 



Dimensions. — PI. XIV, fig. 22, the type specimen, measures — 

 Antero- posteriorly . . .48 mm. 



Dorso-ventrally .... 55 mm. (estimated). 



Locality. — -England: the Carboniferous Limestone of Dent, Yorkshire. 



Observations. — I am not convinced of the value of A. Ruthveni as a species. 

 The type, a left valve in the WoodAvardian Museum, is imperfect, the umbones 

 and that region of the shell being lost; but the markings and the large depressed 

 ears make me suspect that the specimen is a large shell of A. interstitialis, which 

 has exactly the same ornament and ears. 



I would again draw attention to the inaccuracy of M'Coy 's figures. That of 

 A. Ruthveni apparently represents a perfect specimen, whereas the whole of the 

 umbonal region and the greater part of the left ear have disappeared. 



Aviculopecten Careollt, sp. no v. Plate XVII, figs. 2-1 — 27. 



Specific Characters. — Shell of medium size, obovate, dorso-ventral much greater 

 than the antero-posterior diameter; the left valve convex, the right flattened. 

 The anterior and posterior margins almost straight, but oblique; inferior margin 



