Vegetative body of laminar form, with apparently dichotomous branches, and agreeing in habit with the recent thalloid Hepaticae, as represented by such a genus as Marchantia.
The name Marchantites is preferable to Marchantia, as the latter implies identity with the recent genus, whereas the former is used in a wide sense and refers rather to a definite form of vegetative body than to a particular generic type.
1. Marchantites erectus (Leckenby). Fig. 49. This species may be described as follows: The thalloid body is divided into spreading dichotomously branched segments, obtusely pointed apically. The slightly wrinkled surface shows a distinct and comparatively broad darker and shorter median band, with lighter coloured and thinner margins.
Fig. 49. Marchantites erectus (Leck.). From the type-specimen in the Woodwardian Museum. Nat. size.
In 1864 Leckenby described this plant from the Lower Oolite beds of the Yorkshire coast near Scarborough, as Fucoides erectus, regarding it as a fossil alga. I recently pointed out that the general appearance and mode of occurrence of the specimens suggest a liverwort rather than an alga, and proposed the substitution of the genus Marchantites[460]. It would, however, be unwise to speak with any great confidence as to the real affinities of the fossil.
The example shown in the figure is the type-specimen of Leckenby[461]: the breadth of the branches is about 3 mm. Under a low magnifying power the surface shows distinct and somewhat oblique wrinklings, the general appearance being very similar to that of some recent forms of the genus Marchantia.
A closely allied species has recently been described from the Wealden beds of Ecclesbourne, near Hastings, on the Sussex coast, as Marchantites Zeilleri Sew.[462].
In a recent monograph on Jurassic plants from Poland, apparently containing much that is of the greatest value, but which is unfortunately written in the Polish language, Raciborski[463] describes a new species of thalloid Liverwort under the name of Paleohepatica Rostafinski. The specimens are barren plants larger than any Jurassic species hitherto described; they agree closely in habit with Saporta’s Tertiary species Marchantites Sezannensis.
2. Marchantites Sezannensis Saporta. Fig. 50. The body is broadly linear and dichotomously branched, with a somewhat undulating margin. Midrib on the dorsal surface depressed, but more prominent on the ventral surface. The upper surface is divided into hexagonal areas, in each of which occurs a central pore. There are two rows of scales along the median line on the lower surface. Stalked male receptacles.