XXII.—Further Observations on the Genus Lyginorachis Kidston

Abstract

The genus Lyginorachis was proposed by Kidston (1923, pp. 18–19) to accommodate isolated petioles which, whilst their structure was similar in some respects to that in the petiole of Lyginopteris, could not be finally identified with the latter genus. Two species of Lyginorachis have been described (Scott, 1923, pp. 57-60; Crookall, 1931, pp. 27-34, pls. i-iii). Both came from Scottish Lower Carboniferous rocks; the one, Lyginorachis papilio Kidston and Scott, from the Cementstone Group (Calciferous Sandstone Series) at Norham Bridge on the Tweed, and the other, Lyginorachis Taitiana Kidston and Crookall, from the Auldton Limestone (Carboniferous Limestone Series) near Lesmahagow, Lanarkshire. Crookall also described a smaller and simpler petiole (loc. cit., pl. ii, fig. 3) as Lyginorachis sp., from the Cementstone Group at the Langton Burn, near Duns, Berwickshire.