612 
APPENDIX A. (LONSDALE ON CORALS.) 
inch : the thickness, so far as it was preserved, was one inch. The columns possessed a nearly uniform 
diameter of two lines. The central plates were separated by small intervals, and they very generally 
ranged across the area of the tubes, but they were occasionally of more limited extent ; in all cases, 
however, there was a great tendency to a uniformity of arrangement and to a slight convex or concave 
curvature. Near some of the superior terminations of the columns, as well as in other parts, were slight 
local irregularities. These central plates occasionally abutted against a well-defined band of small, arched 
or vesicular laminae, but they more frequently blended with the complex structure of the sides of the tubes. 
Divisional walls, formed of a distinct compact layer, were noticed to a very limited extent, and even 
then not satisfactorily ; nor are any represented by MM. de Koninck and Michelin, in the species 
figured by them ; but in the Mendip Hill fossil, a solid partition was noticed in some portions. The 
boundary or exterior of adjacent columns in Michelinia concinna, was formed, apparently, or so far as it 
could be ascertained, of a blending of upturned margins of central plates, with occasionally an inner vesi- 
cular lining. The wall, believed to be thus composed, was not often exhibited, and to the extent to which 
it was examined, no vertical furrows were noticed ; but it was clearly perforated by foramina (fig. 3 a), less 
regular in character than those of Favosites, but with smooth edges, and plainly not referrible to acci- 
dental fractures. Their lineal arrangement in two instances gave the walls the semblance of being fur- 
rowed. These boundaries exhibited no tendency to separate in a vertical fracture, and the upper surface 
presented instances of a vesicular filling-up between some of the columns. That the polypes, which 
formed the mass of columns, did not enjoy a perfect blending of animal existence, is, however, evident 
from the not unfrequent occurrence in specimens of Michelinia, of considerable intervals, as noticed by 
M. de Koninck ( opus nit. p. 30), and even of extremely narrow spaces ; and it is therefore probable that 
the intermediate matter above mentioned was deposited by occasional extensions of the polype. These 
characters are considered of importance in leading to a correct separation from Favosites of many corals 
which otherwise might be referred to that genus. 
The terminal cups were not well-exhibited ; but in the best cases the polygonal boundary was sharp, 
and the hollow so lined by laminae as to be perfectly circular. 
With respect to the mode of producing additional columns, the principal specimen of Michel, concinna 
afforded abundant proofs of increase along the marginal boundary ; and it is believed that instances of 
interpolated young columns were noticed. 
Locality and Formation. — East of Ust-Koiva, on the Tchussovaya. Carboniferous limestone. 
Cyathophyllum turbinatum, Goldf. 
Petrefacta, &c., p. 56. pi. 16. fig. 8. (1826.) 
Silurian System, part ii. p. 690. pi. 16. fig. 11. (1839.) 
A group of three stems, agreeing perfectly in their bi-areal structure with the fossil figured in Mr. 
Murchison’s work. 
Locality and Formation Petropavlofsk, N. Ural. Upper Silurian. 
The above species and Cyathophyllum dianthus, as represented in the ‘Silurian System’ (pi. 16. fig. 12), 
and exhibited in a specimen of the Gothland coral, described by Fougt (Amoen. Acad. vol. i. Corallia 
Baltica, fig. 10), as well as referred to by M. Goldfuss in his account of the species, being believed to 
represent the typical structures of the genus Cyathophyllum, the present inquiry has suggested the 
necessity of grouping certain analogous corals, which agree in the bi-areal composition, and probably in 
the mode of reproduction with Cyath. turbinatum and Cyath. dianthus, but which exhibit peculiarities not 
so limited to one modification as to enable their being assigned to single species. 
