MICROSCOPIC FOSSIL BRYOZOA. 269 
Crista Jounstoniana. Lign. 89, fig. 3, 10, 10°.— The 
minute recent corals thus designated are allied to Flustra, 
_ but separated from that genus by the cells being disposed in 
a single series, and united by connecting tubes. I notice 
this genus to direct attention to a very curious polypidom 
from the Greensand of Maidstone, presented to me by Mr. 
Bensted. The specimen is attached to a fragment of shell. 
The cells, five of which are represented, fig. 10, are elliptical, 
with the aperture above, and towards one extremity ; they 
are united by very slender, hollow filaments: fig. 3, two of 
the cells seen from above x 250 linear; fig. 10, the same 
seen in profile.* I have named this species C. Johnstoniana, 
as a tribute of respect to the author of the admirable works 
on British Zoophytes, previously noticed. 
The fragmentary relics of numerous minute and elegant 
corals, constitute a considerable portion of the mass of some 
of the white chalk strata; several genera of these zoophytes 
are figured in Mr. Dixon’s beautiful work, and described by 
Mr. Lonsdale. Attached to the surface of shells, &c., and 
sometimes standing erect in little crannies, or hollows, of the 
flints, many beautiful corals may often be detected with the 
aid of a lens. By brushing chalk in cold water, and exam- 
ining the deposit, the student will probably discover several 
of the species figured in Zign. 89, which we proceed to de- 
scribe. 
Rerepora (Lace-Coral). Lign. 89, fig. 13.-—A very thin 
calcareous polyparium, disposed like net-work in foliaceous 
and branching plates; cells opening either on the upper or 
inner side. 
These are an elegant tribe of corals, of which many species 
occur in the Chalk formation at Maestricht, in the white- 
chalk of England, in the mountain limestone of Yorkshire, 
* J refer this fossil to the genus Crista with some hesitation; per- 
haps Hippathoea would be more correct, but all the described species 
of the latter are branched. | 
