Confervites.--The cellular aquatic plants named Confervæ are sometimes found in transparent quartz pebbles, and in chalk, appearing as delicate simple or branched filaments, which, by the aid of the microscope, are seen to be articulated. Seven species are described by authors, but the vegetable nature of some of these is doubtful. A beautiful species in Chalk, first noticed by the late Samuel Woodward, Esq. (author of the Geology of Norfolk), is here figured. [Illustration: Lign. 8. Confervites Woodwardii; _nat._ _Chalk. Norfolk._] [Sidenote: 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. [Illustration: 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.