CARBONICOLA SUBROTUNDA. 65 



9. Carbonicola gibbosa, sp. nov. Plate VIII, figs. 1, 1 a, 1 b, 2. 



Specific Characters. — Shell massive, very gibbous, somewhat oblique. Anterior 

 end short, swollen, and deeply excavated above by the lunule, so that it is almost 

 bluntly pointed. The posterior end comprises most of the shell, and is very 

 tumid, becoming gradually compressed toward the posterior end into the border. 

 This end is curved obtusely and rapidly downwards from the end of the hinge-line 

 to meet the inferior border at a blunted angle, which would be a right angle were 

 it not rounded. Inferior border very slightly convex for the greater part of its 

 length, becoming slightly concave posteriorly. 



The hinge-line, if produced anteriorly, would form a very acute angle with the 

 inferior border, and is somewhat arched and comparatively long. The external 

 ligament extends nearly to the posterior end of the hinge-line. The umbones are 

 very gibbous and obtuse; with the beaks curved forwards and downwards, con- 

 tiguous, raised above the hirige-line, and excavated anteriorly by a deep and broad 

 lunule, which is heart-shaped. Surface covered by concentric lines of growth and 

 strise, which are oblique to the long axis of the shell. Interior not seen. 



Dimensions : 



Antero-posteriorly . . . .45 mm. 



Dorso-ventrally . . . .32 mm. 



Laterally . . . . .31 mm. 



Locality. — Shale above the roof of the Moss Coal, Longton. 



Observations. — The only other form of Carbonicola which approaches the one 

 under description is A. turgida, of which it is quite possible that it may be a very 

 large variety. The lunule of the species under description is comparatively 

 wider and deeper. I only know of two specimens of the shell. From the cabinet 

 of Mr. J. Ward, of Longton, who obtained them from the roof of the Moss Coal, 

 North Staffordshire Coal-field. This shell must be very rare indeed. 



Fig. 1, PI. VIII, is a very perfect specimen, and I have given three views of it. 



Fig. 2, PI. VIII, is a less perfect form, and has been somewhat crushed. 



10. Carbonicola subrotunda {Brown). Plate VIII, figs. 3 — 7. 



Pachtodon subbotundus, Brown. Ann. Mag. Nat. Hist., 1843, vol. xii, pi. xv, 



fig. 8. 

 Unio subbotundus, Brown. Fossil Conchology, 1849, pi. lxxiii, fig. 22. 

 Pachtodon Dawsoni, Brown. Ann. Mag. Nat. Hist., 1843, vol. xii, pi. xv, fig. 10. 

 Unio Dawsoni, Brown. Foss. Conch., 1849, pi. lxxiii, fig. 3. 

 ? — Garner. Nat. Hist. Staffordshire, 1844, pi. e, fig. 20. 



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