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FLUSTRA. ESCHARA. 267 
which the animal can protrude its tentacula and upper part. 
(Figures of the living polypes of Flustre, Wond. p. 605, 
pl. vi. fig. 6, 7.) 
Many species of Flustre occur in the British strata: the 
encrusting forms are attached to echinites, shells, &c. ; the 
foliaceous are imbedded in chalk, sand, sandstone, &c. In 
Mr. Morris’s Cat. Brit. Foss. ten species are enumerated ; 
none of these are from formations below the Chalk. I have 
selected for illustration a /lustra attached to an echinite 
from Lewes. Lign. 89, fig. 5, represents a small portion of 
' the natural size ; and fig. 4, a few cells magnified, to show 
their form and arrangement. <A foliaceous zoophyte, appa- 
rently a bryozoon, is abundant in the Sussex and Kentish 
chalk, and is often disposed in angular folds. It is gene- 
rally of a ferruginous colour, and, from its friable texture, 
it is probable the original consisted of a membranous poly- 
pidom or calcareous substance ; specimens sometimes extend 
over several square inches of the chalk. It is common in 
the chalk-pit at Offham, near Lewes.* 
Escuara.t—In these zoophytes the polyparium is encrust- 
ing or foliaceous, calcareous and brittle ; the cells are thick- 
ened on their outer margins, and havea small, depressed,round 
aperture. They are arranged in two series of planes, adhering 
together, the cells on each surface exactly corresponding. 
Species of Escharz are found either in flints, or attached 
to echinites, and other bodies ; they have the appearance of 
patches of flustre, but with a lens may be distinguished by 
the symmetrical juxtaposition of the cells on the opposite 
_ sides of the polyparium. 
* In my South Down Fossils, pl. xv. fig. 6, a specimen of this kind 
is described as a Ventriculite, V. quadrangularis, An admirable 
_lignograph of a remarkable example is given by Mr. Toulmin Smith, 
under the name of Brachiolites angularis ; it presents ten deep, flat, 
angular folds, and has radicle and lateral processes; see “On the 
Ventriculide,” p. 93. 
+ So named from a supposed resemblance to an eschar, 
