V 



1871.] 



878 



DAWSON — DEVONIAN TREB FERNS. 



4. RnACHioPTEHis, n. sp. 

 (Plato XII. fig. 7.) 



Along with the above, in Dr. Newberry's collection, is a singular 

 fragment enclosed in a large nodule of chert from the Comiferous 

 Limestone. It shows clearly about 8 inches of the base of an im- 

 mense petiole, from 4 to 2 inches in breadth, and attached to shreds 

 of tissue, which seem to represent a part of the stem torn away with 

 it. Its structure is preserved, and consists of delicate large-celled 

 parenchyma, with slender bundles of vessels, about eighteen of which 

 are visible. In structure they are very similar to those of the last 

 species; but the scolariform vessels are accompanied by more 

 woody tissue. They are parallel in the distal end of the fragment, 

 but near its base become tortuous and branching. In the part 

 which represents the stem, or possibly part of its roots, they as- 

 sume the form of cylindrical rods of parenchyma with a central 

 bundle of vessels. In form and outward marking it resembles 

 R. gigantea of my Royal-Society Memoir; but in the latter the 

 structure is not preserved. The present specimen must have be- 

 longed to a tree fern of grander proportions than either of those 

 previously noticed. 



In the cellular tissue of some parts of this great petiole there are 

 numerous round granules, resembling those figured by Corda in his 

 description oi Protopteris Cottai *, and supposed by that writer to be 

 grains of fossilized starch. Mr. Carruthers has more recently de- 

 scribed similar starch-granules in the tissues of an Eocene fernf . 

 Whether the granules in the cells of the present specimen are really 

 remains of starch, or merely rounded siliceous concretions, such as 

 are often found In the cells of silicified plants, I am by no means 

 certain. Perhaps the fact that similar round grains are seen in the 

 interior of some of the woody fibres militates against their organic 

 character. They are certainly not markings on the cell-walls, but 

 spherical bodies contained within the cells ; and if starch-grains, 

 they may claim to be the oldest known, being of Middle Devonian 

 age. 



5. N(EGGEBATniA GILBOENSTS, H. Sp. 



. (Plate XII. fig. 8.) 



Leaf rhombic-obovate, with a broad base. Nerves or radiating 

 plicoe nine in number, not forked, and with fine strije between them. 

 Length 3^ inches. Breadth 2^ inches. 



This leaf occurs in the collections of Mr. Lockwood, from Gilboa. 

 It belongs, without doubt, to the provisional genus Noeggarathia, 

 and seems to have been bent in a conduplicate manner, and clasping 

 or decurrent, on a stem or branch. It does not seem to have been 

 a fern ; but beyond this I am not inclined to hazard any opinion as 

 to its affinities. 



* Beitrage, pi. 49. 



t Quart. Journ. Geol. Soc. Aug. 1870. 



