Fig. 266. Laccopteris polypodioides (Brongn.). (× 14.) (Brit. Mus.)
In habit this species closely resembles Matonia and Matonidium, the long petiole divides distally into several spreading pinnatifid pinnae with linear ultimate segments ([fig. 278], A). Circular sori (indusiate?) occur in a single row on each side of the midrib containing 12–14 large sporangia ([fig. 266]) characterised by an obliquely vertical annulus. The midrib of the pinnules gives off secondary veins at a wide angle and these form a series of elongated meshes parallel to the median rib, as in the recent genus Woodwardia; forked and anastomosing branches are given off from these to the edge of the lamina ([fig. 267]).
Fig. 267. Pinnules of Laccopteris. (Enlarged.)
- A, B. From the Inferior Oolite of Yorkshire.
- C. From the Inferior Oolite of Stamford. (British Museum.)
The specimen shown in [fig. 268] is probably a young frond of this species.
A very similar, possibly a specifically identical plant, was described by Leckenby from English Jurassic rocks as Phlebopteris Woodwardi[875], the distinguishing features of which are the greater number of lateral veins and the smaller sori ([fig. 267], A).
The name Microdictyon was proposed by Saporta[876] for pinnules differing slightly from those of Laccopteris in venation characters: he included Laccopteris Woodwardi in this genus, but such differences as are recognisable in the venation hardly justify the use of a distinct generic title. Similarly, specimens described by Debey and Ettingshausen[877] from Lower Cretaceous rocks of Aix-la-Chapelle as species of Carolopteris may also be included in Laccopteris.
