Fig. 51. Muscites polytrichaceus Ren. and Zeill. (after Renault and Zeiller).
1. Muscites polytrichaceus Renault and Zeiller. In this species the stems are about 3–4 cm. long and 1·3 m. broad, usually simple, but sometimes giving off a few branches, and marked externally by very delicate longitudinal grooves. The leaves are alternate, closely arranged, lanceolate, with an acute apex, gradually narrowed towards the base, 1–2 mm. long, traversed by a single median vein.
One of the French specimens, on which the species was founded[474], is shown in fig. 51, and the form of the leaves is more clearly seen in the small enlarged piece of stem. The authors of the species point out that the tufted habit of the specimens, their small size, and the membranous character of the leaves, all point to the Musci as the Class to which the plant should be referred in spite of the absence of reproductive organs.
Among recent mosses, the genus Rhizogonium,—one of the Mniaceae,—and Polytrichum are spoken of as offering a close resemblance to the fossil form. The type-specimen was found in the Coal-Measures of Commentry, and is now in the Museum of the École des Mines in Paris; the figure given by MM. Renault and Zeiller faithfully represents the appearance of the plant.
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It has been suggested[475] that some small twigs figured by Lesquereux[476] from the Coal-Measures of North America as Lycopodites Meeki Lesq., may possibly be mosses. The specimens do not appear to be at all convincing, and cannot well be included as probable representatives of Palaeozoic Musci. Lycopodites Meeki Lesq. bears a close resemblance to the recent Selaginella Oregana shown in fig. 48, C.
From Mesozoic rocks we have no absolutely trustworthy fossil mosses. The late Prof. Heer[477] has quoted the occurrence of certain fossil Caterpillars in Liassic beds as indicative of the existence of mosses, but evidence of this kind cannot be accepted as scientifically sound. In 1850 Buckman[478] described and figured a few fragments of plants from a freshwater limestone at the base of the Lias series near Bristol. Among others he described certain specimens as examples of a fossil Monocotyledon, under the generic name Najadita. Mr Starkie Gardner[479] subsequently examined the specimens, and suggested that the Lias fragments referred to Najadita should be compared with the recent freshwater moss Fontinalis. In this opinion he was supported by Mr Carruthers and Mr Murray of the British Museum. In a footnote to the memoir in which this suggestion is made, Gardner refers to a moss-capsule from the same beds, which he had received from Mr Brodie. Through the kindness of the latter gentleman, I have had an opportunity of examining the supposed capsule, and have no hesitation in describing it as absolutely indeterminable. It is in the form of an irregularly oval brown stain on the surface of the rock, with the suggestion of a stalk at one end, but there are no grounds for describing the specimen as a moss-capsule, or indeed anything else. The type-specimens figured by Brodie and subsequently referred to a moss are now in the British Museum; they are small and imperfect fragments of slender stems bearing rather long oval leaves which might well have belonged to a moss. The material is however too fragmentary to allow of accurate diagnosis or determination.
2. Muscites ferrugineus (Ludg.). This species possesses a slender stem bearing crowded ovate-acuminate leaves. The capsules are cup-shaped, borne on a short stalk, with a circular opening without marginal teeth. This fossil was first figured and described by Ludwig[480] from a brown ironstone of Miocene age at Dernbach in Nassau. The author of the species placed it in the recent genus Gymnostomum, and Schimper[481] afterwards changed the generic name to Sphagnum, at the same time altering the specific name to Ludwigi. The evidence is hardly strong enough to justify a generic designation which implies identity with a particular recent genus, and it is a much safer plan to adopt the non-committal term Muscites, at the same time retaining Ludwig’s original specific name. Without having examined the type-specimen it is impossible to express a definite opinion as to the accuracy of the description given by Ludwig; if the capsule is correctly identified it is the oldest example hitherto recorded of a fossil moss-sporogonium.