Palaeobotany of the Mesophytic II. New and noteworthy jurassic ferns from Yorkshire

Diagnosis: Frond at least bipinnate. Rachis up to 2 mm broad, longitudinally grooved. Pinnae alternate or subopposite, up to 1,5 cm broad (normally 1 cm), longest one 5 cm long but without apex. Pinnae arising at intervals of 1-2,5 cm, and at an angle of 30-60°. Pinna-rachis thin. Pinnules arising at an angle of 45° at intervals of 1-6 mm, alternate, katadromic. Pinnules always united basally. Pinnules in the lower (or middle) part of the leaf linear, up to 1,5 cm long (normally 1 cm) and up to 4 mm broad (normally 2 mm). Apex obtuse, margin entire, slightly narrowed near the base, basal margin decurrent as a narrow wing along the pinna-rachis. In the upper part of the leaf pinnules smaller, 4 mm broad, 6 mm long, deltoid and slightly falcate. Proximally the pinnae are pinnulate, the pinnules becoming first laterally fused and then forming an entire pinna. Venation: Midrib arising at a small angle near the basal edge of the pinnule and bending outwards or, sometimes, straight to the apex. Lateral veins arising in katadromic order or nearly opposite, at intervals of 1—2 mm and at an angle of 40°, simple or once forked half-way towards the margin; branches diverging.