276 
GEOLOGY OF THE FIRST DISTRICT. 
Alabama. Here we behold a new creation of genera of shells, saurians and fishes. The 
genera Baculites, Hamites, Crioceratites, Cirrolites (nob.), Scaphites, all cephalopodous uni¬ 
valves, appear for the first time in the cretaceous series. Dr. Morton has referred this division 
to the greensand of Europe; and indicates one shell as identical with a British species (Pec- 
ten quinquecostatus), which occurs both in chalk and greensand. The following fossils I 
believe to be common to the European and American lower cretaceous strata: 
Shells. 
1. Pecten quinquecostatus. Chalk and greensand. 
2. Ostrea vesicularis. Chalk. 
3. — falcata (O. larva, Nillson.) 
4. Grypheea vomer (Ostrea lateralis, Nillson). Chalk. 
5. Trigonia aliformis (T. thoracica, Morton). Greensand. 
6. Ammonites conradi (A. sussexiensis, Mantell). Chalk marl. 
7. Nautilus expansus (N. dekayi, Morton). Chalk marl. 
Fishes. 
8. Galeus pristodontus. Chalk. 
9. Lamna acuminata. Chalk. 
10. — mantelli. Chalk. 
Saurians. 
11. Mosasaurus. Maestricht strata. 
“ The middle division of this system was first discovered and described by Dr. Morton. 
It consists of grey marl, alternating with a limestone which appears to be of a kind of oolitic 
or granular texture; but when examined with a glass, this structure is found to be due to 
innumerable minute nummulites and small corallines. A band of this limestone runs through 
the greensand district of southern New-Jersey, from New-Egypt to Salem. It contains 
several of the fossils of the lower division, but others which are peculiar to it. It is remark¬ 
able that no trace of ammonites has been discovered in this limestone, the greensand seeming 
to be the highest limit of the genus. I discovered this formation at Wilmington in North- 
Car olina. 
“ The upper division of the cretaceous system is composed of a chalky limestone, which 
I was the first to trace in the Southern States, and to collect the group of its organic remains 
which have been described by Dr. Morton. These as a group, were ascertained to be unlike 
any observed in Europe, and to point to a passage or connecting link between secondary and 
tertiary deposits. The only extinct genus of shells found in it is Plagiostoma ; but not one 
recent species occurs, and which are found in the overlying lower tertiary strata. This lime¬ 
stone contains those numerous vertebras of the Zeuglodon (Basilosaurus, Harlan), which are 
not uncommon in Alabama, and characterize the formation. This division occupies a portion 
of South-Carolina, near the seaboard, and of Georgia south of Augusta, but its great deve- 
