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APPENDIX A. (LONSDALE ON CORALS.) 
to a certain extent with that of the axis of the same species ; but in all the details of differential structure 
Lithost. astroides was well distinguished from the three other Russian corals belonging to the genus. 
The only specimen examined was a silicified, irregular mass, three and a half inches in height and 
three in breadth and depth. It consisted wholly of somewhat confusedly aggregated columns, averaging, 
in terminal stars, seven lines in diameter ; and though it was so completely charged with silex for half 
an inch from the surface that no characters could be clearly traced, yet the interior was so free from 
infiltered mineral matter, that all the solid framework of the original coral was fully exposed (fig. b ). 
(1.) The axis (fig. b) was completely united structurally with the inner zone, not merely by being es- 
sentially composed of expansions of interstitial plates, but by vertical extensions also of the lamellae, which 
connected perpendicularly the successive, conical, twisted laminae. It therefore could not be exhibited 
naturally or in a fracture as a distinct body, in the same way as in Lithost. emarciatum, L. mammillare, or 
L. floriforme ; nor could the conical lamina; be clearly detached from each other as in the second of those 
species. The characters exhibited by the axis varied with different periods of development. In one 
state it presented only a medial plate with slightly twisted, spiral extensions of lamella, but in another 
of a broad semi-conical lamina on each side the medial line, forming a perfect cap and concealing all other 
component parts. 
(2.) The inner zone with the axis united as one body was well shown in a weathered surface (f fig. a), 
presenting a long cylinder, flanked by a diverging, feather-like structure. No such separation was clearly 
exhibited in the fractured interior of the specimen which retained perfectly the characters of the original 
coral, but the commencement of the transverse perpendicular lamina; (f fig. b ) marked the boundaries 
of the two areas. The cylinder consisted of a conically-twisted centre, the axis, with radiating lamellae 
which were united within the zone horizontally and obliquely by the interstitial plates, and at the peri- 
phery by vertically connecting arched laminae. 
(3.) The outer zone differed in characters from that of the other species included in these notices by 
being traversed completely by perpendicularly persistent, thin lamellae ; and in the arched, highly inclined, 
diverging plates being not merely very narrow, on account of their thorough intersection, but individually 
of very limited range, resembling the small vesicular laminae in the outer area of Cyathophyllum and 
other genera (* fig. b). 
One instance of a young column considerably advanced towards maturity was observed within the area 
of an old column. 
Localities and Formation. — Pinega (sixty versts west) ; Carboniferous limestone. Tchussovaya banks, 
above Ust- Koiva; Carboniferous limestone. The latter specimen was a very imperfect siliceous cast, 
which did not permit its characters to be clearly ascertained, but it was believed to belong to this species. 
Lithostrotion floriforme, Fleming. 
Columns irregularly aggregated; axis cylindrical, spirally twisted, detachable; inner zone, breadth small, 
lamella alternately broad and narrow ; interstitial plates horizontal or inclined ; outer zone, vesicular 
lamina broad, highly inclined, traversed on the upper surface only by lamelliferous plates extending to 
the periphery ; outer wall in general broadly ribbed, sometimes broadly furrowed ; terminal cup deep ; 
boss prominent, spirally twisted; surrounding depression lined by lamella of inner zone ; band of outer 
area more or less inclined; vesicular plates broad, crossed wholly by sharp, vertical, unequally pro- 
jecting laminae ; boundary ridges prominent, crenulated. 
