Kirkbya Urei, Jones., 1859

11. Kirkbya Urei, Jones. View in CoL

(Pl. III. fig. 19.)

Kirkbya Urei, Jones, 1859 , Trans. Tyneside Field-Club, vol. iv. p. 136.

Kirkbya Urei, J. N K., 1867 , Trans. Geol. Soc. Glasgow, vol. ii. p. 220; and 1871, vol. iii. Suppl. p. 29.

Kirkbya Urei, Jones A Holl, 1869 , Ann. A Mag. Nat. Hist. ser. 4, vol. iii. p. 225.

Kirkbya Urei, Junes, 1870 , Monthly Microscop. Journ. vol. iv. p. 185, pl. Ixi. f. 15 a, b.

Kirkbya Urei, Armstrong and others, 1876, Catal. W.-Scot. Foss. p. 15.

Oblong, with ends rounded and nearly alike, and of equal height to the rest of the valve, height equal to two thirds of the length, strongly ribbed concentrically, thick-shelled. Dorsal border straight and four fifths of tin; maximum length; ventral border straight or very slightly concave, and sloping evenly up into the curvature of the extremities. There are three strong concentric ridges on each valve; the two outer ­ most of which (speaking of the single valve) are marginal, and follow more exactly the contour of the valve, while the third forms, as it were, an escutcheon in the centre and is attached to the second, or inner one of the two marginal dorsal ridges; within the escutcheon is usually a more delicate, sharply bent ridge, U- or V-shaped, with the subcentral oval pit at its base. The surface is strongly reticulated, the meshes often being more or less rounded and irregular in size. Edge view (lateral contour) compressed ovate or suboblong, with the anterior end the narrower. Viewed from below, little is seen of the carapace but the four ventral ridges with intermediate reticulated spaces and the ridges of the escutcheon; the view from above (fig. 19, b) shows a broad obtusely angulated dorsal area, widest at the posterior end; along this area the two marginal ridges arc continued (in less strength), single rows of meshes separating them from each other. Length inch.

This is one of the smaller forms of the genus. Some spe ­ cimens are relatively longer than others, and some have the extreme dorsal and ventral regions well rounded, and so are more oval and less rectangular in figure than in perhaps more typical examples. The ridges vary in strength and sharp ­ ness, being sometimes very high and wall-like; the central concentric ridge, or escutcheon, as we have termed it, is occasionally imperfect ventrally. There are also other slight variations, as in all the Kirkbyae ; but, on the whole, this is a well-marked and characteristic species. It is of interest also on account of its having been discovered by the Rev. David Ure, of Ruthcrglen, in the Carboniferous-Limestone series of Western Scotland, so far back as 1793 or before. Specimens of it, along with other Microzoa, were sent by him to his friend Dr. John Hunter, in London, who placed them in his Museum, now the Hunterian Museum, Royal College of Surgeons, where they were noticed by one of us more than sixty years afterwards.

Localities.—England. Carboniferous-Limestone series: Dun Quarry near Lowick, Skellygatc (Ridsdale), Scremcrston, in Northumberland; Holker Park, Lancashire.

Scotland. Carboniferous Limestone (Lower): Brockley, High Bhmtyre, Head of Mouse Water, Capelrig Quarry, Brankumhall Quarry, and elsewhere in Lanarkshire; Craigenglen, Stirlingshire; Murrayficld Old Pit, AVhitebaulks Quarry, Linlithgowshire; Burlage Quarry, East Lothian; Darcy Limestone Quarry, Edinburghshire; Inverted Quarry, Coast near Abden and Seafield Tower, Wilkieston Quarry, Coast cast of St. Monans, Sunnybank Quarry, Glenniston Quarry, in Fifeshire. Carboniferous Limestone (Upper): Robroystone.

Besides the foregoing species there are some other forms which additional material and further study may show to belong to Kirkbya . Certain of these forms (from the Lower Carboniferous beds) are rather perplexing in their double and almost equal relationship to Beyrichia and Kirkbya . To these we shall recur at some future opportunity.

Note.— In the Zeitschrift deutsch. geol. Gesellsch. 1867, Dr. R. Richter has figured and described Kirkbya, Richteriana (p. 224, pl. v. figs. 1 -3) and K. collaris , sp. nov. (p. 225, pl. v. figs. 5, 6), from the Zechstein of the neighbourhood of Saalfeld.