Sigillaria youngiana KIDST., 1894

Sigillaria youngiana KIDST., 1894

1894a Sigillaria youngiana KIDST. , p. 261, pl. 6, fig. 2.

1966 Sigillaria youngiana KIDST. ; Crookall, p. 372, pl. 83, fig. 10.

D e s c r i p t i o n. Stem with undulating 3–6 mm wide ribs. Leaf scars 2.5 mm long, 3 mm wide, occurring a short distance higher than the widest parts of ribs where they cover ca. ¾ of rib width; scar with emarginate upper margin, rounded lower margin, and prominent, downwardsprojecting lateral angles; lateral lines extend downwards from lateral angles for 4–8 mm. A central (vascular) cicatrix and two lateral (parichnos) cicatrices occur just above the middle of the scar; no evidence of infrafoliar parichnos. Ligule pit occurs just above leaf scar and from which there is a plume of 2–5 short radiating lines.

R e m a r k s. Only one specimen of this species has been reported, which we have not been able to see directly, but which is well-illustrated by Crookall (1966). The phyllotaxy of the stem is not completely typical of Sigillaria and Koehne (1904) compared it with Lepidodendron volkmannianum STERNB. , although the leaf scars of the latter tend to be much larger.

O c c u r r e n c e. Possil Ironstone (Limestone Coal

Formation), Robroyston Colliery, Lanarkshire.