Caddy Buddy books

It is to be remembered, also, that this intermixture has hitherto
been recognised, not in the Middle Triassic limestones of the
Muschelkalk, in which--as the oldest Triassic beds with marine
fossils--we should naturally expect to find it, but in the St
Cassian beds, the age of which is considerably later than that
of the Muschelkalk. The intermingling of old and new types of
Shell-fish in the Upper Trias is well brought out in the annexed
table, given by Sir Charles Lyell in his 'Student's Elements of
Geology' (some of the less important forms in the table being
omitted here):--
GENERA OF FOSSIL MOLLUSCA IN THE ST CASSIAN AND HALLSTADT BEDS.
Common to | Characteristic of | Common to
Older Rocks. | Triassic Rocks | Newer Rocks.
| |
Orthoceras. | Ceratites. | Ammonites.
Bactrites. | Cochloceras. | Chemnitzia.
Macrocheilus. | Rhabdoceras. | Cerithium.
Loxonema. | Aulacoceras. | Monodonta.
Holopella. | Naticella. | Sphoera.
Murchisonia. | Platystoma. | Cardita.
Porcellia. | Halobia. | Myoconcha.
Athyris. | Hoernesia. | Hinnites.
Retzia. | Koninckia. | Monotis.


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