Kirkbya spinosa, Jones & Kirkby.

Gunther, Albert C. L. G., Dallas, William S., Carruthers, William & Francis, William, 1885, The Annals and Magazine of Natural History, Including Zoology, Botany, and Geology, Reptiles and Batrachians from Brazil, LONGMANS, GREEN, AND CO.; SIMPKIN, MARSHALL, AND CO.; KENT AND CO.,; WHITT AKER AND CO.: BAILLIERE, PARIS: MACLACHLAN AND STEWART, EDINBURGH: HODGES, FOSTER, AND CO., DUBLIN: AND ASHER, BERLIN: TAYLOR AND FRANCIS, pp. 1-96 : 185-186

7. Kirkbya spinosa, Jones & Kirkby.

(Pl. III. figs. 12 a, b.)

Kirkbya spinosa, J. & K., 1867 , Trans. Geol. Soc. of Glasgow, vol. ii. p. 220; 1871, vol. iii. Suppl. p. 29.

Kirkbya spinosa, Armstrong and others, 1876, Catal. W.-Scot. Foss, p. 45.

Ovate-oblong, oblique at the ends, swollen in front, rather compressed behind, less than twice as high as long. Dorsal border straight, and a fourth less than maximum length; ventral border curved; anterior extremity rounded and most prominent above; posterior extremity obliquely rounded and most prominent below. The anterior portion of the valve is much the thickest. The subcentral pit is sometimes longi ­ tudinal, sometimes transverse and almost a sulcus, which is occasionally divided by the upper ridge. Two, and even three, ridges traverse the valve longitudinally, one either above or across the pit, the others below; the upper and mid ridges terminate in strong spines, which curve upward and forward. A very delicate rim bounds the free margins. Edge view (lateral contour) subcuneiform (fig. 12, b). Shell thin; sur ­ face smooth (?). Length inch.

In some specimens (probably old and worn) the ridges are almost obsolete; otherwise this species seems subject to little variation. Mr. James Thomson discovered this species.

Localities.—England. Carboniferous-Limestone series: Steeraway, Salop; Calces, Cumberland; Scremerston and Ridsdale, Northumberland; Holker Park, Lancashire.

Scotland. Carboniferous Limestone (Lower): Craigenglen, Scullengour, in Stirlingshire; Garpel Water, Ayrshire; Paiston Quarry, East Lothian. Carboniferous Limestone (Upper): Ravenscraig, Fifeshire.