NUCULA PALM.E. 185 



being evidently the cast of a young N. attenuata, and that figured as N. longirostris 

 is synonymous with the N. Isevirostrum of Portlock, which was described one year 

 previously. 



I refigure M'Coy's type of N. longirostris, PL XV, fig. 16. 



There can be no doubt of the identity of the shell figured by Salter as Gtenodonta, 

 sp., from the roof of the Great Mine Coal, Ashton-under-Lyme. Salter says of 

 it, " All that can be said about this smooth form, with a few concentric lines of 

 growth, is that it does not belong to either of the common Mountain Limestone 

 species, such as C. attenuata, G. tumida, C. brevirostrum, &c. ; but it is too imperfect 

 to name." Seeing that no species of the genus quoted occurs in the Mountain 

 Limestone, this statement is somewhat vague. 



This species resembles Nucula undulata more closely than any other ; but the 

 narrow transverse diameter, and the subacute, lanceolate posterior end, and 

 smaller size of the shell are sufficient to establish the identity of this species. 



Nucula palmm, Soiuerby, 1825. Plate XIV, figs. 36, 36 a. 



Nucula palm.e, Sowerby, 1824. Min. Conch., vol. v, p. 117, pi. 475, fig. 1. 



— — Fleming, 1828. Hist. Brit. Animals, p. 403. 



— — Morris, 1843. Cat. Brit. Foss., p. 95. 



— palm^a, Brown, 1849. Illustr. Foss. Conch., p. 185, pi. lxxvi, fig. 39. 



— PALM.&, Bigsby, 1875. Thesaur. Devonico-Carboniferus, p. 303. 



— — Etheridge, 1888. Brit. Foss., part 1, Palasoz., p. 287. 



Specific Characters. — Shell transverse, convex, nuciform, only very slightly 

 inequilateral. The anterior end is comparatively large, with a rounded border. 

 The inferior border is convex in front and behind, but almost straight for the 

 greater part of its extent. The posterior end is bluntly rounded. The hinge-line 

 is angular. 



Interior. — The hinge is multidenticulate, with about sixteen anterior teeth 

 and sixteen posterior, separated by a small triangular cartilage-pit, the teeth 

 becoming smaller as they approach the umbo. 



Exterior. — The surface is covered with fine concentric lines of growth. 



Locality. — Derby. 



Dimensions. — The type specimen (PI. XIV, fig. 36) measures — 



Antero-posteriorly . . . .22 mm. 



Dorso-ventrally .... about 13 mm. 



Observations. — Owing to imperfections in the type, and to the fact that I am 

 not able to identify any other shells as belonging to this species, I am not able to 

 give further details. Indeed, I am very doubtful if the species really belongs to 



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