APPENDIX A. (LONSDALE ON CORALS.) 
595 
To suggest grounds for specific distinctions in fossil corals of so simple a composition is extremely diffi- 
cult, especially when characters dependent upon the limits of growth have not been ascertained. So far, 
however, as the describer s observations have extended, the distinctions in the arrangement of the dia- 
phragms afford apparently one means for inferring differential structures ; those variations implying, it 
is presumed, peculiarities in the form of the polypes. In the remarks upon Chat, radians it is shown, 
that the diaphragms are distributed in concentric or parallel bands, and often at considerable distances, 
the bands being composed of a single series of plates, or of a variable number of closely-situated lamina;, 
whilst in the account of Chat. Petropolitanus it is explained, that the diaphragms are irregularly distri- 
buted over the whole area of a vertical section. In other fossils belonging to the genus, but not included 
in this notice, distinct peculiarities were observed. It is further suggested, that the characters exhibited 
by well-preserved terminal edges of the tubes might afford some aid in specific determinations ; a protected 
surface of Chat, radians, which presented probably a periodical renewal of growth, having the edges sur- 
mounted by a series of very prominent tubercles. 
The above remarks are not offered with the idea, that the characters alluded to could constitute alone 
specific distinctions ; but they are advanced with the hope, that they may assist in discovering essential 
structures. 
Figure 9 a in the Plate A., illustrative of the corals, exhibits the sub-divisional lamina; mentioned in 
the remarks on the mode of producing additional tubes within the area of pre-existing. 
Cluetetes radians, Fischer. 
Mass elliptical or semi-globose ; tubes divergent, polygonal ; diaphragms in parallel bands variously composed ; 
superior edges of tubes generally even, sometimes tuberculated. (Plate A., fig. 9.) 
Cheetetes radians, Fischer, Oryc. dc Moscou, p. 160. pi. 36. f. 6. (Miatchkova) ; Milne Edwards, 2nd 
edit. Lamarck, Anim. sans Vert., ii. p. 459. 
This fine and apparently abundant coral is believed to differ from the carboniferous limestone fossils of 
England, referrible to the same genus. One of the specimens examined in preparing these memoranda, 
was a portion of an irregularly elliptical mass, those measurements which might be termed the semi-axis 
major, or greatest altitude, and the semi-axis minor being respectively four and two and a half inches 
(fig. 9.). The tubes diverged rapidly in the direction of the latter line, but the curvature gradually 
decreased as they assumed an upward range, disappearing in the greater axis. The exterior of the spe- 
cimen presented considerable evenness of surface, but a variable amount of curvature. The diameter of 
the tubes was about one-third of a line, but the length in some cases appeared to be equal to the altitude 
of the specimen. 
Perfect terminations to the tubes, or such as might be assumed to be perfect, were not noticed, the edges 
being either fractured and worn or in a state of development, presenting boldly-serrated or tuberculated 
margins. The mouths were more or less occupied by calcareous spar, according to the amount of infil- 
tered matter ; in some cases they were also partially or wholly crossed by the transverse laminae. 
The bands of diaphragms ranged nearly parallel to each other and to the surface of the specimens. 
The distance between them was generally from one and a half to two lines, and in some cases no distinct 
band could be detected in an interval of four lines, hut near the surface the distance did not exceed one 
line. In all cases, however, whether the bands were composed of a single series of plates forming a con- 
tinuous arched line, or of many plates more or less closely disposed, and attaining, it is believed, in some 
rare instances nearly half an inch in thickness, there were well-defined, relatively broad intervals, in 
which it was rare to detect even a single isolated plate. The broadest bands which were noticed, were 
situated at the base of one specimen and near the circumference of another. 
