DESCRIPTION OF CHALK CORALS. 309 
sents a side of the same branch not very deeply worn down, major tubes being 
comparatively few, and tubuli very numerous. The commencement of a side 
ranch is also shown close to the back. 
The only signs of an exterior affected by age occurred in the specimen fig. 3, 
(fig. 3c gives a portion on an enlarged scale,) which, except near the upper ex- 
tremities of the main branches, presented no furrows or tubes deprived of their 
outer lamina, but oblique, oval apertures, surrounded by the intermediate struc- 
ture ; and this condition is believed to have arisen from an increase in that por- 
tion of the coral, whereby the part of the tube which in earlier stages was ex- 
posed became overlaid. 
The fossil represented in Tab. XVIII. B. figs. 6 to 6 g, consists of numerous, 
long, diverging and anastomosing branches, which are slender, round, smooth and 
simple in their composition during an early state, but afterwards thick, verrucous 
and complex by the addition of unequal cellular layers ; the mouths of the cells 
are round or oval, and often truncated at the proximal extremity, not raised, 
irregularly distributed, and closed under certain conditions ; internally the cells 
are elongated and inclined downwards, and centrally in the younger or axeal 
portion of a branch, but in the wart-like additions they are short and variously 
inclined ; the intermediate structure is porous or reticulated. 
In some of the preceding particulars the English coral resembles M. Michelin’s 
Ceriopora papularia’, found in the “‘ craie chloritée”’ of France, as in the general 
mode of growth, the external characters of the branches, the two sets of pores, 
and the thickening by irregular layers being similar; but in a specimen of 
Cer. papularia liberally presented to the compiler of these memoranda, the earlier 
conditions of the fossil were not exhibited, nor are they delineated in figs. 7 a, 7 6; 
no traces also of cellular mouths closed by an appendage like that noticed in a 
subsequent paragraph were detected, though M. Michelin says the pores “‘ dans 
certains états de pétrification sont invisibles.”” The want however of ascertained 
agreements in those two points, the means of comparison being moreover limited, 
is not deemed sufficient to separate the English fossil from the French generi- 
cally or even decidedly as respects the species ; nevertheless it will be necessary 
to offer a few remarks on the assignment to Ceriopora. 
 Iconog. Zoophyt. p. 124. pl. 32. f. 7 a, 7 6. 
