22 
enable the societies to come to a right decision. As 
it is, the Conference decided to invite the societies— 
first, to confirm by their separate vote the joint resolve 
of their delegates, and then to give proof of their in- 
terest in the attainment of the object by nominating 
one or more members to act on a committee to be ap- 
pointed for the purpose. The evil of such a course is, 
that much valuable time is lost in correspondence and 
negotiation before any practical step is taken in the matter. 
After all, however, the delay may be useful in ripening 
opinion on the subject. What is wanted in the steps 
eventually to be taken is energy of purpose and prompti- 
tude of action, for we are sure that the object in view will 
be eminently conducive to the welfare and progress of 
Science in the United Kingdom. 
FOSSIL OYSTERS 
Monographie du Genre Ostrea—Terrain Cretacé. Par 
Henri Coquand, Docteur és-Sciences, Professeur de 
Geologie et Mineralogie. (Paris: Baillitre, 1869.) 
‘Oa the many able geologists whom France has pro- 
duced, few have had better opportunities of observa- 
tion, or have availed themselves of them to better pur- 
pose, than the author of this monograph. Distinguished 
alike by his skill and long experience asa paleontologist, 
and by his extensive knowledge of practical geology, M. 
Coquand has laboured long and well, and far and wide—not 
only in Provence, and Italy, and Germany, but in far distant 
regions in Spain and Africa, in valleys and mountains never 
before resounding to the blows of the geologist’s hammer, 
Those who are only acquainted with the chalk as it is 
seen exposed in quarries and cuttings on the green downs 
and wolds of England, can form but a very imperfect 
notion of its true character. As M. Coquand has shown ina 
paper lately read before the Geological Society of London,* 
the chalk of England, extensive as we are accustomed 
to regard it, is but a fragment when compared with that 
which is seen in the South of France. The utmost thick- 
ness of the English Cretaceous beds is found to be about 
goo feet, while in Provence the same, or rather the equiva- 
lent beds are more than 4,000 feet thick. In England we 
are accustomed to arrange the chalk into three or four divi- 
sions, while in France their more extended development re- 
quires an entirely different arrangement, and thus we find 
no less than eleven different beds, the character and limits 
of which are now ascertained with great accuracy. 
The French strata being thus so much more largely 
developed than the English, the character of the fauna 
is, as might be expected, infinitely more varied. The 
difference of nearly three thousand feet is principally 
yepresented in France by several marine and freshwater 
beds altogether unknown in England. In some places, 
as at La Cadiére and Martigues, we find extensive beds 
of Hippurites and Radiolites—fossils almost unknown 
in England, lying ranged in close order as when 
they lived; and again, while we have been accustomed to 
regard the chalk as altogether of marine origin, we find in 
Provence a district of about 250 square miles, in which the 
upper chalk strata of England and the Charentes of France 
are represented by freshwater deposits 1,400 feet thick. 
These contain several hundred species of land and fresh- 
* Quarterly Journal G. S., Aug. 1869, vol. 25, part 3. 
NATURE 
| AZay 12, 1870 
water shells unknown elsewhere, associated with beds of 
lignite as compact as our own Newcastle coal, and like it 
worked extensively for fuel. Both from the palzontological 
and the geological evidence it would seem as if, at some 
time, while our Cretaceous deposits were interrupted and 
stationary, others of great magnitude, with a succession of 
fauna essentially differing, as well from our own as from 
each other, were accumulating in the South of France, 
alternately depressed and elevated—sometimes a deep 
sea, sometimes a great lake, and not improbably at one 
time dry land. 
After a careful study of the Cretaceous systems of 
many countries, M. Coquand, undeterred by the dread 
of taking charge of a family at once so numerous and so 
troublesome, has now been induced to prepare this mono- 
graph of all the Cretaceous oysters wherever found, to be 
followed by like monographs of the Tertiary, Jurassic, 
Triassic, and Permian formations. It is, we believe, 
the first, or at least the most important attempt to give a 
| synopsis of any one genus occupying so extensive a range. 
The results of M. Coquand’s researches are sufficiently 
striking ; he describes no less than 255 distinct species of 
chalk oysters (including Gryphea and Exogyra), and of 
these he has given excellent figures in an atlas of 75 
plates, in folio. As regards England, he has disclosed 
the poverty of the land as compared with our neighbours. 
Our chalk oyster beds have been examined as assiduously 
as the French, but they have been found much less prolific, 
While France possesses 115 well-marked species, England. 
according to Mr. Morris’s catalogue, can show but 25, all 
of which, except one (O. triangularis of Woodward), 
seem to be found also in France. 
Nor is the range of some species less remarkable than 
their abundance. Two of them (vesiculosa, and ungulata 
or Zarva) appear to be altogether cosmopolitan ; the former 
being found alike in England, France, Algeria, Belgium, 
Spain, Poland, Russia, Sweden, North America, and 
Mexico ; and the latter having been also traced through all 
these countries (except Poland and Mexico), and extending 
its range also to India. 
But while some species are thus prone to wander, othe 
are to be noted for their domestic habits. Out of 49 
American species, five only have been met with in Europe; 
and of 27 in Russia, and 23 in Spain, no less than 1o in 
each of these countries are not found elsewhere. 
It seems evident from our author’s observations, that 
so far as these fossils are concerned the several zones of 
chalk which he has described are divided by “a hard and 
fast line,” marking the limits of each as clearly as the 
Tertiaries are separable from the Secondary rocks. Of 
the several Dordonien species, not one is found in the 
Campanien beds, and of ninety-five found in the Cam- 
panien none are found in the lower beds, and the same 
observation applies to each of the seven or eight inferior 
deposits. Although it transcends all our powers of cal- 
culation to form even a conjecture, much less an approxi- 
mate estimate of the ages of ages that should be allowed for 
the creation (or, if that word be not allowable, for the 
introduction or evolution) of these various forms, and the 
extinction of their predecessors, we may yet gather from 
these materials a somewhat better, although still utterly 
inadequate notion of the extreme deliberation, so to speak, 
exhibited in building up this portion of the earth’s fabric. 
