102 BRITISH FOSSIL CORALS. 
regularly centrifugous towards the margin of the common mass. In some specimens 
they are separated by very large, shallow depressions, containing numerous calices con- 
fusedly arranged (fig. 17); in most they become more numerous, and approximate so as to 
be separated only by the breadth of three or four calices (fig. 1), and in others they 
multiply so much, especially towards the circumference of the corallum, that each valley 
contains only a single series of calices (fig. 14). The calices are not originally arranged, 
either in concentric or radiate series, but irregularly grouped together (fig. 1, 1d). The 
centre of each calice is rendered very distinct by the existence of a small, well-defined 
fossula; but they are completely confluent by their circumference, and the septa pass 
without any interruption from one visceral chamber to another. ‘The septal radii thus 
disposed ascend the above-mentioned ridges, and there become parallel; those of the 
opposite sides meet at the apex of these cristiform productions, and unite there with- 
out ever presenting any trace of a furrow or other separation between them (fig. 1c). The 
Columella is rudimentary, and represented only by one or two papilla, which appear to be 
merely the inner denticulations of some of the septa. There are only two complete septal 
cycla; sometimes, but rarely, a few tertiary septa also exist, and the total number of these 
radiate laminz is therefore twelve, fourteen, and sometimes sixteen. They are all rather 
thick ; their edge is strongly crenulated, and they are united together laterally by nume- 
rous isolated synapticule. The secondary septa are not as long as the primary ones, and 
often become united to them by thew imner edge. Some of the septa are straight, but 
most are more or less bent at the place where they pass from one corallite to another. The 
breadth of the calices does not much exceed a line. 
This fossil is abundant at Steeple Ashton, and exists in the collections of the Museum 
of Practical Geology, Mr. Bowerbank, Mr. Walton, Mr. D. Sharpe, and the Museum of 
Paris. We are inclined to think that the coral mentioned by Mr. J. Phillips under the name 
of Meandrina,' but not described by that geologist, is referable to this species; it was 
found at Malton. We have also seen in Mr. Sharpe’s collection a fossil from this locality, 
which appears to be a Comoseris irradians, but is too ill preserved to be recognised with 
any degree of certainty. 
The genus Comoseris has been established by M. D’Orbigny’ since the introduction to 
this Monograph was printed. It was formed with a species that had been figured by M. 
Michelin under the name of Pavonia Meandrinoides. It differs from all the meandrini- 
form astreinze by the mode of union of the septa, having synapticulz, as in Fuagie, instead 
of dissepiments ; it, at the same time, differs from Agaricia,‘ Oroseris, Protoseris, and 
Lophoseris, by its massive form, and the existence of a complete epitheca on the surface of 
the basal plate. 
1 Geol. of Yorkshire, vol. i, p. 126. 
° Note sur des Polypiers Fossiles, p. 12, 1849. 
° Tconogr. Zooph., tab. xxii, fig. 3. 
* Introduction, p. xlix. 
