CORALS FROM THE GREAT OOLITE. 123 
specimen here figured is much weather worn, and has lost its epitheca as well as the edge 
of the trabicular septa, which assume the appearance of moniliform costal striae. The 
scleerenchymatous nodules that constitute these styliform septal processes or trabicule are 
placed nearly at equal distances from each other in the same series and in the adjoming 
series, so that when they occupy a large surface they appear to be arranged in a very 
regular manner according to three straight lines: one almost vertical, and the two others 
oblique and crossing each other at right angles, (fig. 64.) Ca/ices quite superficial ; the fossula 
are not deep, but are well defined and placed at a considerable distance from each other. 
'The septo-costal radia are numerous (about thirty or forty), very thin, broad, especially those 
that are placed perpendicularly to the edge of the corallum, almost equal in size, rather 
closely set, completely confluent, and formed of a series of nodular styliform processes as 
already stated. The specimen which is figured in this work, and belongs to Mr. Walton’s 
rich collection, is about one inch high and two broad; the corallites are about one and a 
half lines in diameter. 
This fossil is found in the Great Oolite at Bradford Hills, and at Dunkerton ; Prof. 
M‘Coy states its having been met with at Minchinhampton. 
Lamouroux, who established the genus A/‘crosolena had very false ideas of its structure 
and zoological affinities. He supposed that the trabicule which constitute the septa were 
tubes bored in a common mass. M. Michelin recognised the resemblance between 
Microsolena and Porites, but placed the former in the genus Alveopora of Messrs. Quoy 
and Gaimard, from which it differs much. . An attentive examination of various specimens 
of the Microsolena porosa, of Lamouroux, found near Caen, and of some other species, 
has enabled us to ascertain that the genus Microsolena must not be discarded but placed in 
the Family of the Poritide, near the genus Coscinarea, from which it differs principally 
by the existence of a common epitheca, and by the septal trabicule bemg placed further 
apart. We also refer to this generical type some species of a somewhat dendroid 
form that M. Michelin placed in the genus Alveopora, and have been considered by 
M. D’Orbigny as constituting two new genera: Dendrarea and Dactylarea.' 
M. D’Orbigny characterises the first of these divisions as Dendriform Microsolena, 
and the second as Dendriform Synastrea, but we have ascertained that the typical 
species of both present the same structure as Microsolena, and the isignificant 
differences which exist between massive, gibbose, or subdendroid forms, are not in 
our opinion of sufficient zoological value to be employed as characteristic of generical 
divisions. 
Microsolena regularis resembles very much, by its general form, Microsolena porosa,’ 
but differs from it essentially by its septa being much more numerous and closer set. 
1 Note sur des Pol. Foss., p. 11. 
2 Lamouroux, Exp. meth., tab. Ixxiv., figs. 24, 25, 26. 
