296 W. Carruthers — The Forests of the Coal Period. 



in tte cabinet of Dr. Millar, has enabled me to refer these fossils 

 with certainty to the cryptogamous Order Equisetacece as near allies 

 of our living Horsetails. 



This fruit, to which I have given the name Volkmannia Binneyi,^ 

 is a small slender cone, composed of whorls of imbricated scales 

 (twelve in each), arranged like the successive whorls of leaves on 

 the branch, so that the scales of one whorl are in a line vsdth the 

 sjDaces between the scales in the whorls above and below. The 

 scales completely conceal the fruit-bearing leaves. These are stalked 

 and peltate, arranged in whorls alternating with the scales, but having 

 only six — half the number of the scales in a whorl. The sporangia, 

 four in number, are borne on the under-surface of the peltate leaves ; 

 their walls are formed of elongated cells, which have in their in- 

 terior a secondary deposit of cellulose proceeding in short truncate 

 processes from the sides of the cell-walls which are in contact, and 

 having the appearance of an incomplete spiral. The sporangia are 

 filled with simple spherical spores, which in the closely-packed 

 sjDorangium appear to be furnished with double cell-walls. In the 

 half-empty sporangia the outer wall cannot be detected, but there 

 appear instead a number of thread-like processes proceeding from 

 the spore like the elaters in the living Horsetails.^ 



A comparison of this fossil cone with the fruit of Equisetum ex- 

 hibits a remarkable agreement in every point of importance. In the 

 form of the fruit-bearing leaves, the arrangement and structure of 

 the sporangia, the form, size, and structure of the spores, even to 

 the possession of hygrometric elaters, both fruits agree. The only 

 difference is that in the modern plant all the leaves of the cone are 

 fruit-bearing, while in the fossil every other whorl retains a form 

 closely approaching that of the normal leaf of the plant. As these 

 envelope and protect the fruit-bearing leaves, they may be held to 

 give to the fossil a somewhat higher systematic position than is pos- 

 sessed by the living genus. This superiority is further exhibited 

 when we contrast the complex structure of the stem, and the free 

 leaves of Calamites with the fistular and sheath-bearing stems of 

 Equisettim. 



III. The stems, branches, and fruit of the genus Lepidodendron, 

 are so abundant in the shales that cover the coal, that the external 

 aspect of this tree has been for a long time well known. Specimens 

 exhibiting structure are more rare, but these also have been met 

 with, so that we know the internal organization as well as the ex- 

 ternal aspect of the fossil.^ 



The stem is composed of a central pith surrounded by a slender 

 cylinder of scalariform woody tissue, and by a large cortical layer 



^ Prof. Schimper has more recently described and figured the same fruits under the 

 name of Calamostachys Binneyana in his Traite de Paleontologie Ve'getale, vol. i. 

 (1869), p. 330. 



2 Mr. Binney has beautiftilly illustrated the structure of the stem and fruit of 

 Calamites in a series of drawings from specimens in his rich collection, published by 

 the Palseontographical Society in the end of last year. 



^ On some Fossil Plants, showing structure. By E. "W. Binney. Quart. Journ. 

 Geol. Soc. Tol. xYiii. (1862), p. 106, PL 4—6. Phil. Trans., 1865. 



