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APPENDIX A. (LONSDALE ON CORALS.) 
To this summary may be added the notice, that the coral is branched, the branches springing from 
germs developed on the side of the parent stem and never resulting from a subdivision of the polype ; 
that each stem and branch is traversed through its whole length by a single lamelliferous tube ; that the 
exterior of the coral was not thickened by a permanently investing mantle, adjacent surfaces only being 
partially united by the extension of a limited mantle ; and that the lamellse are simple, but bi-plated and 
numerous. 
By these characters and the internal structure, Lithodendron may be easily distinguished from (1) 
Oculina, (2) Den drophy Ilia, (3) Caryophyllia and (4) Cladocora. From the first by the continuous, 
central, lamelliferous tube ; from the first and second by the absence of external thickenings arising from 
a permanently investing mantle ; from Caryophyllia, as restricted by Ehrenberg, in the branches not re - 
sulting from a subdivision of the polypes ; and from all the four genera by the peculiar central diaphragms, 
inclined upwards against the axis, as noticed by Prof. Phillips in his description of species, and represented 
in his illustrations of the genus. (Geol. Yorks., part ii. pi. 2. figs. 17, 18.) 
Lithodendron costatum, sp. n. 
Stems closely clustered, cylindrical, strongly ribbed; lamella simple, variable ; interspaces crossed by arched 
and inclined plates ; central diaphragms sloped upwards, not arched; axis spindle-shaped; terminal 
cup deep, lamella not very prominent, unequal ; height of central boss less than depth of cup. 
Fig. a. represents the mode of branching, and of the occasional union of branches or stems. 
Fig. b. Vertical section magnified, to exhibit the general characters of the interior. 
This species is chiefly distinguished by the neat longitudinal ribs. The specimen examined was about 
two and a half inches in width and one and a half in breadth, and contained parts of twenty-five closely 
aggregated stems. The height of the largest portion did not exceed three quarters of an inch, and its 
greatest diameter was three lines. Only two lateral shoots were noticed, and neither of them was in a 
position to permit the mode of connexion with the parent stem to be fully ascertained. The more favour- 
ably exposed case exhibited transverse sections of the main stem and of the lower extremity of the attached 
branch. At the junction there was no clear demarcation between the two, but a white, rather excentric 
line and an imperfect blending of lamellse. The other branch (fig. a), which was fully exposed, as 
respected position and mode of growth, exhibited from its divergence, a diameter equal to that of the 
main stem. A perfect transverse section of the connecting animal secretion, presented a repetition of the 
structure within the tube, or an outer extension, from each surface, of the lamellse, with intermediate 
plates, and at the junction there was a strong white line. 
An internal vertical section (fig. b) not quite through the centre displayed at the opposite edges an 
irregular band of inclined, curved, or vesicular plates, bounded on each side by an unequal, but more 
solid layer. Within these bands, intersections of vertical lamellse were partially exhibited, but the greater 
portion of the area was traversed by the edges of up-turned plates or diaphragms, sometimes single, more 
