SPONGES, GRAPTOLITES, CORALS. 83 
Lichenaria.] 
Class © ACTINOZOA.* 
Order ZOANTHARIA. 
Sub-order MADREPORARIA, 
Section MADREPORARIA APOROSA, 
Family ASTRAQID AN, 
’ LICHENARIA TYPA, gen. et. sp. nov.+ 
PLATE G, FIGS, 10-13. 
Corallum growing in small, irregular, hemispheric colonies, not exceeding 20 mm 
in diameter, attached by its entire under side to species of monticuliporoids. Ad- 
dition of new corallites takes place, either interstitially or along the periphery, from 
underneath the marginal individuals. Walls of the corallites thin, imperforate. 
Corallites polygonal, inconstant, small but variable, the average adult size about 
1 mm. or a little less in diameter, but in the largest specimens may vary from that 
size to 1.75 mm. in diameter. Tabulz always few, perhaps occasionally wanting ; 
when present they are horizontal and complete. Septa not developed; rarely two 
or three very faint longitudinal lines can be observed on each face of the calyx. 
We know of no compound massive coral in Lower Silurian rocks with which 
this species need be compared. All have more or less strongly developed septa 
excepting Lyopora favosa Nicholson and Etheridge, jun.{ In that species the septa 
are “rudimentary, often wanting in individual calices, varying in number from two 
or three up to ten or twelve or more, always abortive, and represented only by 
rough and blunt ridges on the interior of the wall.” (Nicholson, op. cit., p. 190.) 
Lyopora favosa differs however from Lichenaria typa in its very much thickened walls 
and in the mode of growth of the colony which was “ rooted at its base to some for- 
eign body, and the diverging corallites seem to have opened over the whole of the 
free surface, no traces of an epitheca having come under my observation.” (Nich- 
olson, op. cit., p. 190.) Species of Columnaria are distinguished from Lichenaria typa 
by their well developed alternately large and small septa, which extend nearly to 
the centre of the corallites in the type species. Columnaria incerta Billings§ is 
*The classification here given for the corals is that of Dr. Nicholson ; ‘Manual of Palawontology, vol. i, pp. 240-345, 1889. 
+Lichenaria from leichen, tree-moss, and aria, the latter portion of Columnaria, its most likely relative. 
+Mono. Sil. Foss. Girvan, p. 26, pl. 2, figs. 1-le, 1878. Nicholson, Pal. Tab. Corals, p. 190, pl.8, figs. 3, 3a ; pl. 9, figs. 2, 2a, 1879. 
Canadian Nat. and Geol. vol. iv, p. 428, figs. 1, 2, 1859. 
