DESCRIPTIVE REMARKS. lxvil 
and with the large variety of Ferns, many of which may have been 
Tree-ferns, evidently formed the principal supply from which our 
valuable Coal-seams have been derived. 
The Carboniferous or Mountain Limestone in certain parts of the 
series abounds in Corals or true Polypi; Carenrerara, the majority of 
these, as well as the Silurian Corals, belong to the division Zoantharia 
rugosa.* Some of the most frequent varieties are figured on Pl. xxxyv., 
viz.: Michelinea favosa, fig. 1, especially characteristic of the Lower 
Limestone shale. Calamopora tumida, fig. 2, a, b, ce, Syringopora re- 
ticulata, fig. 3, a, b, a small tubular branching and reticulated species 
occuring in hemispherical bunches. Zaphrentis cylindrica, fig. 4, a 
large simple or turbinated Coral, very frequent in the Lower Limestone 
shales of the North of Ireland. Amplexus coralloides, fig. 5, a, b, also 
a large simple cylindrical Coral, very characteristic of the Irish Carboni- 
ferous Limestone. Lithostrotion striatum (formerly named L. basalti- 
formis), fig. 6, a, b, a compound species, in which the corallites, from 
their close proximity, assume a hexagonal form, like a basaltic column, 
hence the name by which it was first known. L. Portlock?, fig. 7, a, b, 
is also a compound Coral, with a more irregular hexagonal arrangement 
and smaller corallites; their astreiform surfaces, caused by the radiation 
of the sept@ from the prominent columella, are beautifully preserved in 
some examples from the Limestone of the North of Ireland. Litho- 
dendron junceum, fig. 8, a, b,c, a group of small branching corallites 
occurring in bunches, is common in the Lower Limestone shales; and 
L. affinis, fig. 9, an aggregation of much larger branching corallites is 
remarkably abundant in some beds of the Carbonifereus Limestone, 
where it occurs in radiating masses with Lithostrolion striatum, several 
feet in diameter; one of these Lthostrotion ‘stools’ is described in 
the explanation to Sheet 145, Geol. Survey of Ireland, p. 28, fig. 10, 
as being 9 feet in diameter. 
As there is some confusion in the definition of the genera Litho- 
dendron and Lithostrotion, we have arranged those species in which 
the corallites are rounded and separate under the former; for ex- 
ample, Lithodendron affints and L. junceum; and those which are more 
compact, haying the corallites in close proximity, or pressed to- 
gether, under the latter, such as Lithostrotion striatum, L. Port- 
locki, &e, 
The remains of Ecuryoprrmara in the Carboniferous rocks are 
referred to three orders only. The Blastocdea is represented in our 
figures by Pentremites Derbiensis, Pl. xxxvi., fig. 1, a, b,c. This 
elegant little fossil we found to be plentiful at the picturesque lime- 
stone cliff of Ben Naughlin, in the demesne of the Earl of Enniskillen, 
Florence Court, county of Fermanagh, some of the specimens exhibit- 
ing the arrangement of ambulacra and ovarian apertures with great 
distinctness. LP. a flatus, fig. 2, is a larger species in which the short 
stalk and petaloid ambulacra are well shown. 
* See Descriptive Remarks, ante p. xxvii. 
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