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APPENDIX A. 
(LONSDALE ON CORALS.) 
Respecting the other genera with which the Kamensk fossil has been stated to have certain resem- 
blances, few remarks only are necessary. 
Internally there is an almost perfect central agreement, except in the occasional irregularities, between 
the proposed genus and many of the corals usually assigned to Cyathopliyllum ; but there is, again, be- 
sides the distinction in the number of areas, the important difference, of one being perfectly bipartite and 
the other proliferous. 
As regards Stylastrcea, the structural details of the interior are also different as respects the areas, and 
the sub-divisional process, if rightly assigned to that genus, is much less perfect than in the Kamensk 
fossil ; in Stylastrsca also the adjacent columns are never laterally united. 
Lastly, while there is a strict accordance in the mode of branching, there is a complete dissimilarity 
internally between the coral which has been under consideration and Caryophyllia. 
Believing, therefore, that the Siberian and English polypidoms are in their aggregated characters gene- 
rically distinct, it is proposed to designate them by the appellation of Diphyphyllum, founded on the two- 
fold resemblance, first noticed in the Kamensk specimens, to Cyathophyllum centrically, and to Caryo- 
phyllia in the mode of branching (bt (jtvqs, duas habeas naturas ; <j>v\Kov, folium) . 
The following generic characters arc suggested : — 
A stony, lamelliferous polypidom : lamella exceeding 12, bi-plat ed ; branched, branches dichotomous ; inter- 
nal structure, tri-areal : 1 , central area, intersected by flat, convex or irregular diaphragms, no persistent 
axis ; 2, intermediate area, traversed vertically by lamella: ; interspaces crossed obliquely or downwards by 
extensions of the diaphragms and subordinate plates ; 3, outer area traversed by lateral extensions of lamella: 
interspaces crossed by arched or vesicular lamina inclined upwards and outwards ; stems not uniformly thick- 
ened by external secretions, but occasionally united when in juxtaposition. 
Diphyphyllum concinnum. 
Stems cylindrical, nearly smooth ; crossed externally by close, fine, waved lines , and stronger , unequal, distant 
bands ; lamella: numerous, variable ,- inner surface of plates furrowed strongly upwards and outwards ; 
central area, diaphragms flat, convex or irregular ■ intermediate area, principal lamella: exceeding 30, 
more or less waved, intermediate very unequal; interstitial prolongations of diaphragms inclined sharply 
downwards, accessory plates nearly horizontal ; outer area, lamella: variable in strength and range, in- 
terstitial plates largely vesicular ; terminal cup deep, lined by edges of the lamella:, no central boss. 
(PI. A. fig. 4.) 
The specimens of this coral which were examined, consisted of one subdivided stem (fig. 4 a, 4 b), and 
several portions of others (fig. 4) ; the larger having a nearly uniform diameter of four and a half lines, 
and the smaller of three and a half lines. The relative proportions of the areas were not quite constant, 
but in one specimen the width of the central was about two lines, and that of each of the others one line. 
The inner surfaces of the lamella: plates agreed almost perfectly with those of Caninia and Stylastrsea ; and 
the lamellae in their extension across the outer area, partook very much of the variable characters exhibited 
in the former genus ; being sometimes alternately broad and narrow, the latter projecting partially into 
the intermediate zone, but sometimes so united to the vesicular lamina; as to form a complicated reticu- 
lation. The boundary wall was exceedingly thin throughout, and exhibited no indications of lateral junc- 
tions. The indications of an axis were very faint, being confined to the occasional appearance of a single 
line in the centre of the area, or to a few instances of conical irregularities in the diaphragms. The 
beautiful example of bifurcation represented in figures 4 a, 4 b, exhibits clearly the connexion between 
such irregularities and the sub-dividing process. The depth of the terminal cup was rather more than 
