SANGUINOLITES TRICOSTATUS. 391 



good specimens are rarely found ; and shells of S. pUcatus from this locality are 

 often deformed, owing to incomplete fossilisation, and appear much foreshortened, 

 and may then appear to have characters quite different from those given in the 

 diagnosis. 



Sanguinolites TRICOSTATUS, Portlocli, sp,, 1843. Plate XLII, figs. 11 — 15. 



Cypbicaedia ? TiiicosTATA, Fortloch, 1843. Rep. Geol. Londonderry, p. 441, 



pi. xxxiv, fig. 17. 

 — — Morris, 1843. Cat. Brit. Foss., 1st edit., p. 8t3. 



Sanguinolites tricostata, iPCoy, 1843. Synops. Carb. Toss. Ireland, p. 50. 

 Cypbicaedia tbicostata, Brown, 1849. Illust. Foss. Conch., p. 199, pi. Ixxsi, 



fig. 13. 

 SoLENOPSis TBICOSTATA, de Ri/ckliolt, 1853. Melanges pak'ontol., pt. 2, p. 62, 



pi. xiv, figs. 7, 8. 

 Sangitinolites TRICOSTATA, Morris, 1854. Cat. Brit. Toss., 2nd edit., p. 223. 



— — (pars), il/' Coy, 1855. Brit. Pal. Foss., p. 507. 



— — Sigsly, 1877. Thesaurus Devouico - Carboniferus, 



p. 313. 

 Nou — — de Koninck, 1885. Ann. Mus. Eoy. Hist. Nat. 



Belgique, vol. xi, p. 84, pi. xv, figs. 14, 15. 



— — Etheridge, 1888. Brit. Foss., pt. 1, Paleozoic, p. 290. 



— — ? Julian, 1896. Carbonifere marin de la France Cen- 



trale, p. 42, pi. x, fig. 14. 



— — ■ Tornquist, 1896. Fossilfiihr. Untei'carbon Sudvo- 



gesen, ii (Abb. geol. Karte Elsass-Lothr., vol. v), 

 p. 125, pi. xix, fig. 17. 



Specific Characters. — Shell of moderate size, inequilateral, transversely oval, 

 moderately gibbose, carinate, with a much-compressed dorsal slope. The anterior 

 end is small, the narrowest portion of the valve in the dorso-ventral diameter, 

 the upper border being much below the level of the umbones. The anterior 

 border is rounded. The inferior border is long, very gently and regularly convex 

 for the greater part of its extent ; but, as the posterior edge is approached, the 

 convexity increases rapidly in amount. The posterior end is obtusely rounded, 

 with some approach to an angle where it joins the lower border. The postero- 

 superior angle is very obtuse. The hinge-line is gently arched, and is 

 considerably shorter than the longest diameter of the valve. The umbones are 

 small, narrow, incurved and twisted forwards, contiguous, only slightly raised 

 above the hinge-line, and situated in the anterior fifth of the valve. 



Passing from the umbo to the postero-inferior border is an oblique, blunt, 

 angular fold, which marks oS" the dorsal slope from the rest of the valve. The 



