102 BRITISH FOSSIL CORALS. 



regularly centrifugoiis 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. la) ; 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. I d). The calices are not originally arranged, 

 either in concentric or radiate series, but irregularly grouped together (fig. 1, 1^). 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 

 M'ithout 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. Ic). The 

 Columella is rudimentary, and represented only by one or two papillce, 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 laminae 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 si/napticulce. The secondary septa are not as long as the primary ones, and 

 often become united to them by their inner 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 cahces does not much exceed a hne. 



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 Avas 

 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 JPavonia MeandrinoidesI' It differs from all the meandrini- 

 form astreinae by the mode of union of the septa, having synapticulse, as in FangicB, instead 

 of dissepiments ; it, at the same time, differs from Afjaricia,^ Oroseris, Protoseris, and 

 Loj)hoseris, 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. 12fi. 



2 Note sur des Polypiers Fossiles, p. 12, 1849. 



3 Iconogr. Zooph., tab. xxii, fig. 3. 

 * Introduction, p. xlix. 



