APPENDIX 
A. (LONSDALE ON CORALS.) 
597 
another of the same form. A mass of a nearly globular shape, two and a half inches in one diameter, 
and three in the other, had the surface almost wholly weathered, and therefore exhibited no clear cha- 
racters ; but internally, the arrangement of the tubes agreed with that of the hemispherical specimen. 
The original walls of the coral were, apparently, almost membranous, and liable under some conditions 
to irregular contractions, as well as considerable deviations in the line of growth ; but in the large, 
globular mass, such inequalities were far less conspicuous. 
J he diaphragms, exposed in vertical sections, of all the varieties of form, were distributed over the 
whole surface, and without the least indication of grouping in bands. In the hemispherical (pi. A., fig. 10) 
and conical specimens, which exhibited considerable irregularities in growth, the disposition of the dia- 
phragms was very unequal ; while in the large globular mass, a portion of which is represented by fig. 10 a, 
the "plates, without observing any definite order, were uniformly distributed. In some portions, however,’ 
of the other varieties the number of plates corresponded ; and the differences displayed, may, it is be- 
lieved, be rightly assigned to circumstances which affected the mode of growth or production of the 
polypes, and consequently modified the distribution of the diaphragms. 
With respect to the development of additional tubes within the area of those which pre-existed, it may 
be stated, that divisional laminte were noticed m transparent, vertical slices of the hemispherical and glo- 
bose varieties, though less distinctly in the latter than the former: and that while, in a similar section of 
the conical specimen, they were not satisfactorily detected, a transverse slice exhibited clearly divisional 
laminae, ranging from opposite planes. The whole of these specimens, moreover, proved clearly the 
powers which the polype mass possessed of extending laterally and producing marginal tubes. 
Chcetetes Petropolitams having been considered identical with Favosites ( Chatetes ) fibrosa, var. globosa, 
of the Eifel, it is necessary to observe, that in vertical sections of a specimen of the latter fossil, which 
belonged to M. de Verneuil’s cabinet, perpendicular, divisional lamina; within the tubes were noticed, also 
fragments of the original coral, exhibiting only interior surface- walls, similar to those of Chat, radians ; 
and it was therefore inferred that the fossil ought to be removed from the genus Favosites. As regards 
the species, it may be stated, that the diaphragms were uniformly rare, without any signs of disturbed 
growth. The height of the specimen was seven lines. 
Chat. Petropolitams is believed to be identical with a globose tubular coral which occurs in the Lower 
Silurian beds of Christiania Bay, Norway. 
Localities and Formation — Nikolsk to Petropavlosk, on the river Volkof; banks of the Siass river; 
ravines of Pulkovka and Popovka, south of St. Petersburgh ; plateau of Czarskoe-celo ; sea cliffs from 
Narva to Reval. Lower Silurian. 
Lithodendron. 
The Lithodendra of English fossil zoologists differ materially in structure from the corals typical of the 
subdivisions of the genus, as originally proposed by Scliweigger (Beobachtungen, Syst. tab. VI.). As 
however those corals have been referred by approved authorities to other established genera, leaving 
Schweigger’s Lithodendron without a representative, and as the continental systematic zoologists who 
have adopted the genus, more or less in conformity with the original proposer’s views, have also included 
in it corals of great diversity of characters, it has been deemed correct in retaining the generic name 
long applied by British geologists to peculiar mountain limestone polyparia, to adopt Prof. J. Phillips’s 
characters, though they differ completely from those of Scliweigger. 
Mr. Phillips’s generic characters are, “cells concave with a prominent central umbo or axis ; lamella' 
generally twisted or extinct near the centre.” Geol. Yorshire, part ii. p. 202. 1836. 
4 H 
