CORALS FROM THE CORAL RAG. 81 
All the specimens which we have met with were worn, and had lost their wall as well 
as their basis ; we are, therefore, unable to decide whether this species was free or adherent, 
and had or had not a complete epitheca. There remains, therefore, some uncertainty relative 
to the zoological affinities of this fossil, but we have referred it to the genus MJondlivaltia 
rather than to the genus Zrochosmilia, on account of its great resemblance to some other 
corals which undoubtedly belong to the genus Montlivaltia, and also because we have as 
yet not met with any species of Zrochosmilia in deposits formed before the cretaceous 
period. 
The genus Montlivaltia, established by Lamouroux, contains a great number of species; 
more than thirty have been described in our Monograph of the family of Astreida, but 
many of them are as yet but imperfectly known. In a note published a short time ago, 
M. D’Orbigny has considered it advisable to form a separate generic division for the species 
which are of a compressed form, and he has given the name of Perismilia to the group 
thus characterised. But this innovation is not, in our opinion, judicious, for, independently 
of there being instances of every intermediate degree between the species with a calice 
perfectly circular (such as Mondlivaltia brevissima), and those in which the great axis of 
the calice is to the short axis as 260: 100, we see no reason for establishing generical 
divisions on a character which, although to a certain degree constant m some cases, is in 
others variable in the different individuals belonging to the same species. We must add 
that no important difference in other parts of the corallum corresponds with the modi- 
fications in the form of the calice. 
Since the publication of the first part of the Monograph, we have been enabled to 
examine a great number of well preserved specimens of J/ontlivaltia, and have been thus 
led to rectify an error which the study of imperfect specimens had led us into; we have 
ascertained, in many species, that the edge of the septa is not entire, as we formerly sup- 
posed, but is crenulate or regularly denticulated. There is, therefore, no longer any reason 
for separating from the genus Monflivaltia the group which we established some years ago 
under the name of Zhecophyllia,’ and the genus Montlivaltia, thus extended, must no 
longer be placed in the section Eusmiline (p. xxii), but be referred to the tribe of the 
Astreine (p. XXXx1). 
Montlivaltia dispar differs from I. deltoides,? M. rudis,* M. cornucopia,’ M. bilobata,® 
! Note sur des Polypiers Fossiles, 1849. 
2 Compt. Rend. de l Acad. des Sce., t. xxvii, p. 491, 1848. 
3 Annales des Nc. Nat., s. 3, vol. x, pl. 6, fig. 3. 
4 Cyathophyllum rude, Sowerby, Trans, of the Geol. Soc., s. 2, vol. iii, pl. xxxvii, fig. 2. 
5 Milne Edwards and J. Haime, loc. cit., p. 298. M. D’Orbigny places this species in his genus 
Ellipsosmilia, (Note sur les Polypiers Fossiles, p. 5,) which is composed of our compressed T’rochosmilia ; 
all the specimens known are in a very bad state of preservation, but we are inclined to think that this fossil 
had a complete epitheca, as is the case with Montlivaltia ; if not, it must be referred to our genus Trochosmilia, 
for the subdivision of which, proposed by M. D’Orbigny, does not appear to rest on suflicient grounds. 
§ Turbinolia bilobata, Michelin, Icon., pl. ]xii, fig. 1; (not pl. 1xi, fig. 7.) 
aly 
