214 
PROGRESS OF THE STUDY OF ORGANIC REMAINS. 
Wednesday, \2th August. 
MR. GRIFFITH GAVE AN ACCOUNT 
OF A MASS OF SHELLY GRAVEL 
IN THE COUNTY OF WEXFORD ; 
THIS DEPOSITION IS VERY EXTEN- 
SIVE, STRETCHING ALONG THE 
COAST FORA DISTANCE OF SEVEN- 
TY MILES, AND ATTAINING A 
BREADTH OF EIGHTEEN. THE 
FOLLOWING IS A SECTION OF THIS 
DEPOSIT : 
5 feet of clay 
7 feet marl clay 
7 feet marl 
7 feet of sand 
1 1 feet of gravel, containing abundance of 
marine shells. 
5. MR. PHILLIPS THEN READ A 
PAPER ON THE GENUS BELEM- 
NITE. 
He observed that such was the progress 
which the study of organic remains had made, 
that no less than one hundred species were now 
known to naturalists ; and of these, about 
thirty -four species hadbeen found in England. 
Shells of this genus are confined to the 
chalk, oolite, and lias, and the results whieh 
their study affords, contrast remarkably with 
the negative indications deduced from an 
examination of the fossil Astaci, One divi- 
sion characterized by a little swelling at 
the apex, and possessing a lateral fissure, 
was confined to the chalk. The species 
which were obtusely mucronate are found in 
the green sand. The species with a groove 
in the back are found in the middle oolite : 
Those with a lateral groove, in the lias, and 
lower oolite ; and those species which are 
destitute of a groove are confined to the lias. 
From these remarks, it appears that not only 
are the species of Belemnite confined to 
certain strata, but that even certain natural 
divisions of the genus are found together in 
the same beds, and in no others. Another 
curious remark is, that species which are 
common in the chalk of the Continent, are 
rare in the chalk of England, and vice versa. 
These remarks were followed up in an 
admirable manner by M. Agassiz, who, from 
a study of the remains of this difficult genus, 
clearly demonstrated that the shell was an 
interior one, analogous to the bone of the 
cuttle fish, and not an exterior shell, as is 
generally imagined. 
Thursday, \3th August. 
7. M. AGASSIZ LAID BEFORE THE 
ASSOCIATION AN ADDITIONAL 
NUMBER OF HIS WORK ON FOSSIL 
FISHES; 
And, in an eloquent address, he gave a 
summary of the geographical conclusions to 
which the study of fossil fishes had conduct- 
ed him ; and expressed his conviction that 
strata might, in all cases, be identified by 
means of the remains of fishes ; or, in other 
words, that each geological epoch was cha- 
racterized by its peculiar and exclusively 
appropriate race of fishes. 
During this part of the proceedings Mr. 
Sedgwick took the opportunity of putting M. 
Agassiz’s knowledge to a severe test. He 
exhibited a specimen containing impressions 
of fossil fishes, and M. Agassiz, after 
explaining the zoological characters which 
distinguish the fishes of different geological 
epochs, at once declared the specimens before 
him had been derived from the new red sand- 
stone. — 
8. Dr. TRAIL THEN READ A PAPER 
ON THE GEOLOGY OF SPAIN. HE 
CONFINED HIS REMARKS CHIEF- 
LY TO THE PROVINCE OF ANDA- 
LUSIA. 
In this interesting country we have every 
variety of rock, from the oldest primary, up 
to the tertiary strata. The mica slate of Anda- 
lusia contains many interesting minerals, 
as iron, glance, and lead ore. This last mi- 
neral is so abundant that no less than 35,600 
tons were extracted in one year. The pri- 
mary rocks are succeeded by secondary sand- 
stones, in whose fissures interesting osseous 
remains occur. These lime -stones extend to 
the opposite coasts of Africa. This lime- 
stone is followed by new red sand-stone, and 
gypsum marl, abounding in salt and saline 
springs. Oolite rocks occur near the anci- 
ent town of Cartua; and chalk, with flints, 
is observed at Labriga. Tertiary and fresh 
water lime-stones also occur, as has been 
noticed by Colonel Silvertop. 
The beds at Valencias vary from 6 to 8 
feet in thickness, and repose on marl and 
gypsum. 
Friday, \^th August. 
9. MR. PHILLIPS GAVE AN ACCOUNT 
OF A SMALL PORTION OF A TER- 
TIARY FORMATION WHICH HAD 
BEEN OBSERVED IN YORKSHIRE. 
10. MESSRS. MURCHISON AND 
SEDGWICK THEN GAVE AN AC- 
COUNT OF THE ROCKS ANTE- 
RIOR TO THE COAL, AND POSTE- 
RIOR TO THE PRIMARY STRATA. 
These rocks, which were formerly distin- 
guished by the absurd term of transition 
strata, have been, unaccountably much neg- 
lected by geologists ; and, unfortunately, the 
use of this term has given rise to much con- 
fusion in geological writings. Mr. Murchi- 
son has, for several years, devoted his time 
to the study of the older secondary rocks, as 
they occur in Wales, while Mr. Sedgwick 
has investigated those of Cumberland. 
According to Mr. Murchison, the older 
secondary rocks of Wales, which he, for the 
sake of convenience, denominates the Silurian 
group, may be classed under three divisions, 
each of them containing its peculiar organic 
remains, and consisting of a great variety of 
rocks. 
In the descending series, and departing 
from the old red sand-stone, we have the 
Ludlow rocks, attaining to a thickness of 
2,000 feet, consisting of crystalline argilla- 
ceous lime-stones, with flags and shales. 
These rocks are followed by the Wenlock 
group, consisting also of limestones and 
shales. These are succeeded by what Mr. 
Murchison has denominated the Caradoc 
