On the occurrence of fish remains in fossil and recent marine deposits

The number of fish remains occurring in fossil marine deposits varies within wide limits. In many deposits they are rather scarce, sometimes even wholly absent, whereas in some deposits they are common or abundant. According to DEECKE (1913, p. 90) they are scarce in many mesozoic marls, and they are wanting even completely in the devonian Helderberg and Oriskany beds and in the jurassic Opalinus and Renggeri clays. The deposits with a. great number of fish remains are divided by DEECKE into different groups. (The groups that refer to brackish and to supersaline water I shall leave out of consideration). The most important group is represented by certain finegrained sediments that probably were deposited near to the shore; very often these are shales (PAUCA, 1933, p. 11). Many of these socalled fish shales are bituminous (permian Kupferschiefer, triassic fish shales of the eastern Alps and Italy, miocene Monterey shales of California, etc.). Besides isolated parts of fish these shales often contain more or less complete specimens.