Lign. 8. Confervites Woodwardii; nat.
Chalk. Norfolk.
FOSSIL FUCOIDS.
Fossil Fucoids.—Of the tribe of Algæ which comprises the sea-weeds that are not articulated, many fossil species occur in very ancient, as well as in modern, fossiliferous deposits. In the Lower Silurian rocks of North America, beds of limestone of great extent are full of a large digitated Fucus (Fucoides Alleghaniensis).[74] The Firestone or Malm-rock of Bignor in Sussex abounds in a ramose variety (Fucoides Targionii, Vég. Foss. p. 56), of which specimens are figured in the vignette of this volume, and in [Lign. 9.]
[74] Figured and described in Dr. Harlan's Medical and Physical Researches: Philadelphia, 1835, p. 393.
Chondrites.—These fossil algæ approach nearest to the living species of Chondrus (hence the name of the genus). The frond is thick, branched, dichotomous, with cylindrical or claviform divisions, with a smooth surface and without tubercles. The substance of the Bignor fossils is a white friable earth, which strikingly contrasts with the dark grey malm-rock that forms the matrix. As the Sussex Chalk Chondrites appear to be distinct from the Tertiary species named by M. Brongniart C. Targionii, I have, at the suggestion of Mr. Morris, substituted C. Bignoriensis, to indicate the locality in Sussex in which I discovered it forty years since. In the chalk-flints ramose fuci occasionally occur, but not in a state of preservation that admits of the determination of the forms of the originals.
Lign. 9.
Chondrites Bignoriensis; nat.
Malm-rock. Bignor, Sussex.
The tertiary marls and limestones of Monte Bolca yield several beautiful species of Algæ, one of which is figured in [Lign. 10]. It is referred to the fossil genus Delesserites (Sternberg), which includes those algæ that have thin, and flat or undulated, smooth, membranous fronds, with a median rib.
Of the little plants comprised in the class of cellular cryptogamia, which have stems, leaves, and fructification, but no true vessels, two or three species of Moss and Liverwort have been met with in tertiary strata. Mosses as well as Fuci are occasionally imbedded in quartz pebbles, in which they appear of their natural colour, and apparently floating in the transparent medium. A beautiful green moss, with a Conferva twined round its base, is figured [Lign. 11, p. 104], from a specimen described by the late Dr. Macculloch. It is supposed to be related to Hypnum (Geol. Trans. vol. ii.).