442 CARBONIFEROUS LAMELLIBRANCHIATA. 



Localitiefi. — England : the Carboniferons Limestone series of Lowick, North- 

 umberland. Scotland : the Carboniferous Limestone series of Ardross. Ireland : 

 the Lower Limestone series, half a mile north of Easky, Bunowna, co. Sligo. 



Ohsermtions. — Unfortunately Baily gave no description with the figure of his 

 species f^. Si/mesii, and the figured specimen has been lost for several years, so 

 that the name cannot be retained, and I have to adopt 8. excisa, de Koninck. 



The less transverse shape, the absence of radiating ribs, and the much 

 depressed, almost beaked posterior end distinguish this shell from all other 

 Carboniferous species of the genus. It is to be noted, however, that the narrow- 

 ing of the posterior end is much more conspicuous in casts. 



It may be remarked that the specimen figured by de Koninck {loc. cif., pi. ix, 

 fig. 14) shows the shell to be equivalved, and that it does not gape. Beushausen 

 calls attention to the fact that this specimen does not show the slit for the 

 ligament posteriorly ; but I would suggest that the boss shown in fig. 14 

 represents the structure, ligamentous or not, which occupied the slit. 



SoLENOMVA cosTELLATA, M'Goy, sp., 1844. Plate L, figs. 7 — 10, 13. 



Sanguinolites costellatus, M'Coy, 1844. Synop. Carb. Foss. Ireland, p. 48, 



pi. viii, fig. 5. 

 SoLEMTA pkiMjEVa, de Vernetiil, 1845. Geol. Russie, vol. ii, p. 205, pi. six, fig. 5. 

 Sanguinolites costellatus, Morris, 1854. Cat. Brit. Foss., 2nd edit., p. 223. 

 SoLENiMTA (pEiMiETA), M'Coy, 1855. Brit. Pal. Foss., p. 519, pi. iii r, figs. 3, 3 rt. 

 SoLENOMYA BADiATA, Meeh and Worthen, 1860. Proe. Acad. Nat. Sci. Phila- 

 delphia, p. 457. 



— — — 186G. Greol. Surv. Illinois, Palseont., 



vol. ii, p. 349, pi. xxvi, figs. 

 10 a, b. 



— — Bigshy, 1878. Thesaurus Devonico-Carboniferus, p. 312. 

 Sanguinolites costellatus, Bigshy, 1878. Ibid., p. 3 LI. 



— — Etheridge, 1888. Brit. Foss., pt. 1, Palaeozoic, 



p. 289. 



Specific Ghavacters. — Transverse, oblong, upper and lower margins almost 

 parallel, very inequilateral, compressed. The anterior end is much the longer, 

 gradually compressed, gapiug, its border somewhat truncate, bluntly rounded 

 below into the lower margin, but above forming a rounded angle with the hinge- 

 line. The longest dorso-ventral diameter of the valve is almost at the anterior 

 end. The inferior border is elongate and almost straight, but near the posterior 

 end becomes more convex. The posterior end is narrowed by the approach of the 

 upper and lower margins (the upper margin descending very rapidly), elliptical, 



