THALLOPHYTES, BRYINAE. 51 



is confirmed in this belief by a letter of Fuchs on the subject of the 

 Chondritae of the Flysch printed in his work 1 . 



The group of Alectoruridae, with the genera Alectorurus, Taonurus, 

 Cancellophycus, Glossophycus, contains a series of remarkable remains from 

 the Silurian up to the Tertiary formations ; they have been admirably 

 figured in the works which have been already so often cited, and particularly 

 in Saporta. Among them is the so-called Cock's-tail Alga (Spirophyton 

 Cauda Galli), which occurs in such abundance in certain beds of the Upper 

 Devonian formation in America, that it has given them the name of Cauda 

 Galli grits.' Descriptions and figures of this fossil will be found in L. 

 Vanuxem 2 . Opinions are much divided on the question whether they are 

 of organic or inorganic origin. Nathorst considers that he has produced 

 analogous forms artificially ; he says on this point : ' The experiment of 

 producing a circular movement in water in a vessel, the bottom of which 

 was covered with fine sand, has supplied me with an excellent imitation 

 of Spirophyton Cauda Gaili ; from a small central cavity irregular arched 

 markings spread on the same side towards the margin, and were not dis- 

 tinguishable from the corresponding structure in Spirophyton.' Unfor- 

 tunately he has given no figure ; and since he assumes of other similar 

 forms that they were produced by worms, or by tufts of plants fixed at the 

 bottom of the sea and moved about by the waves, he gives us the im- 

 pression of not being quite clear in his own ideas on the subject. The 

 figure which he gives of an analogous form produced by a worm 3 has 

 only a very general resemblance to the fossils which we are considering. 

 There are also cases in which these Taonurae do not merely project in 

 half-relief, but form perfectly separable casts between the layers, the margin 

 being arched over and thickened into a cushion 4 . I do not quite see how 

 we can conceive such a cast to be formed by eddies in water ; but I am as 

 little able to discover in these remains the Siphoneae which Saporta sees 

 in them. 



A few words only are required here for the fossil Mosses, which being 

 obtained almost entirely from Tertiary and Quaternary deposits and being 

 closely allied to recent forms are of scarcely any interest to the botanist. 

 Most of those hitherto found are barren ; a single capsule only appears to 

 be known, and this has been described by Ludwig 5 as Gymnostomum 

 ferrugineum from the Miocene haematites of Dermbach in Nassau ; Schim- 

 per considers 6 it to belong to Sphagnum, and calls it Sph. Ludwigii. The 

 reader may be fitly referred to Schimper's work for an account of the 

 tolerably numerous barren Hypneae and other remains of Mosses which 

 have been found in a fossil state. The type of Marchantieae is known in 



1 Nathorst (1), p. 94. 2 Vanuxem (1), p. 128. 3 Nathorst (1), p. 77. * de Saporta 



(1), t. 8, f. 3, and (3), p. 91. s Ludwig (2). B Schimper (1), vol. i, p. 252. 



E 2 



