416 CARBONIFEROUS LAMELLIBRANCHIATA. 



Ecxterior. — The surface is ornameDted iu the same way as the interior. Shell 

 very thin. 



Dimensions. — PI. XLIV, fig. 10, a specimen from the Limestone of Lowick in 

 the Woodwardian Museum, measures — 



Antero-posteriorly . . . .38 mm. 



Dorso-ventrally . . . .11 mm. 



From side to side . . . .4 mm. 



Localities. — England : the Limestone of Lowick, Northumberland. Scotland : 

 first Limestone on the shore east of Kinghorn, Fife, Lower Limestone group. 



Observations. — At first sight it might be thought that the shell figured in 

 PI. XLIV, fig. 10, was the young of 8. plicatus ; but apart from great differences 

 in the comparative measurements, the position of the anterior adductor muscle- 

 scar, so far backwards and quite in the hollow of the umbones, at once makes it 

 certain that the shell belongs to a different genus. 



This species has somewhat the characters of Palasosolen, Hall, but the umbones 

 are not placed so far forwards as in that genus ; on the other hand the general 

 shape of the valve is rather more like the type of Palaeosolen than of Solenopsis. 



8. parallehis is at once distinguished from 8. minor by the absence of narrow- 

 ing of the posterior end of the approach of its upper and lower borders. 



8olenopsis vetusta, Goldfuss, from the Stringocephalenkalk of Gerolstein, has 

 a close affinity to 8. parallela, but its lower border is much more convex. The 

 shell of 8. vetusta, ^gnred by Beushausen, 'Abl. Konigl. Preuss. Geol. Landes- 

 anstalt,' Heft 17, n. f . ; Die Lamell. des rheinischen Devon, pi. xviii, fig. 3, has 

 even more resemblance than Goldfuss's figure. 



At present I have only been able to examine a few specimens of the species, 

 one of which from Lowick is in the Woodwardian Museum, Cambridge, and the 

 others are in the Museum of the Geological Survey of Scotland ; the latter being 

 very small and young specimens. 



Allorisma, King, 1849. 



HiATELLA, Fleminf/, 1828. Hist. Brit. Auim., p. 4G1. 

 Venus, Phillips, 1830. Geol. York., pt. 1, p. 209. 

 Sanguinolaria, Portlock, 1843. Geol. Rep. Londonderry, p. 434. 

 PosTDONOMTA, Portloclc, 1843. Ibid., p. 745. 

 Sanguinolaria (pars), Morris, 1845. Cat. Brit. Foss., p. 100. 

 Allorisma, de Verneuil, 1845. Geol. Russie, vol. ii, Paleout., p. 296. 



— Morris, 1845. In Strzelecki, Pliys. Desc. New South Wales, p. 270. 



— I^inff, 1849. Monogr. Perm. Foss., p. 196. 

 Mtacites, Morris, 1854. Cat. Brit. Foss., 2nd edit., p. 213. 



Non Allorisma, Shumard, 1855. Eep. Geol. Surv. Missouri, pt. 2, p. 20G. 

 Sangcinolites (pars), M'Coy, 1855. Brit. Pal. Foss , p. 507. 



