APPENDIX A. (LONSDALE ON CORALS.) 
599 
frequently intermingled with subordinate though similar lamina;. A strong white line ranging not quite 
through the centre, and against which the up-turned plates abutted, marked the position of the axis. In 
the description of Lithodendron concameratum, some further details respecting the internal structure of the 
genus will be found. 
Transverse sections of the stems gave very variable characters. At the circumference there were 
generally between the lamellae, one or more series of arched laminae intersections of the plates, men- 
tioned in the remarks on the vertical structure. The lamella-, alternately broad and narrow, varied 
considerably in their extension ; and the central area was likewise very unequal in dimensions, as well 
as in the number and in the curvature of the intersected diaphragms. The spindle-shaped axis was also 
not uniformly bold. 
Locality and Formation. — Perimishel, south of Kaluga. Carboniferous limestone. 
Lithodendron annulatum, sp. n. 
Stems clustered, cylindrical, faintly ribbed, strongly but irregularly annulated, with subordinate, fine, waved 
lines; central diaphragms waved, upward inclination not great ; axis oval. (Plate A., fig. 5.) 
Lithodendron annulatum attained probably considerable dimensions, though the largest specimen exa- 
mined had an altitude of only three inches, the diameter of the tubes being almost uniformly five lines. 
It is distinguished from other species, known to the describer, by its bold, rounded, but unequal annular 
ridges, with subordinate fine lines, and by the waved contour of the central plates (fig. 5 a). The only 
additional point of structural interest observed in this species was the proof, that the cementing layer 
between adjacent stems was secreted during the growth of the coral — the bold annular ridges being 
in some cases almost confluent, and the fine lines of growth being distinctly traceable from the surface 
of one stem across the connecting layer to the surface of the next. 
Localities and Formation. — River Issetz, east of Ekaterinburg; Ilinsk, on the Tchussovaya. Carboni- 
ferous limestone. 
Lithodendron concameratum, sp. n. 
Stems aggregated, cylindrical, slender, faintly ribbed, very rarely branched, occasionally united; lamella 
simple, equal in breadth ; interstitial plates arched; central diaphragms dome-shaped, more or less crossed 
by vertical lamina ; axis compressed, not persistent, formed of union of lamella ; walls without an inter- 
nal vesicular layer. 
This curious coral differs in some respects from the ordinary forms of Lithodendron, yet it possesses 
all the essential elements of the genus. It is distinguished specifically by the dome-shaped diaphragms. 
The specimen examined, was three inches in height and one and a half in breadth and depth : it consisted 
of closely aggregated stems which had a nearly uniform diameter of two lines, and ranged upwards almost 
perpendicularly. The lateral connexions, so far as they could be ascertained, were few and of limited 
extent. Only one very imperfect fragment of a branch or side-shoot was observed. 
The outer wall, as exposed in vertical and transverse sections, was thin and without a trace of vesicular 
lining. The external ribs in a few protected stems were distinct and round. The lamellae, about twenty 
in number, sprung directly from the inner surface of the wall, and were simple in structure and uniform 
in breadth in any single transverse section, but their characters varied according to the nature of the 
section and the state of preservation. The perfect diaphragm formed a complete dome with a slight 
spindle-shaped opening or impression in the centre. A well-preserved under surface was surrounded 
by a circle of narrow lamellae apparently perfect, as the edges presented an almost uniform, arched 
outline ; between these lamellae were the interstitial commencements of the diaphragms, and from their 
edges grooves ranged upwards for some distance towards the centre of the dome, but there was not the 
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