[From introduction:]
Recent studies in the soft ocean bottoms of the San Pedro Basin, California, in depths of 4 to 495 fathoms, have disclosed the presence of an unknown, greatly diversified metazoan invertebrate fauna. Its geographic extent to north or south of the region studied is not yet known, but the horizontal limits of its components have been established within
the area studied (Hartman, 1955).
Through extensive studies over many years, it has been established for European seas that the animals living within the bottom, or the Infauna, are very nearly the same in all areas, from Arctic to tropical seas (Thorson, 1951, pp. 481-489). Distinct communities of greater or lesser extent have been named, and the presence of dominants and recessives has been noted so that the composition of a given area is predictable within limits.
Current studies on the Infauna of ocean bottoms of southern Californian waters have shown that the bottom-dwelling animals differ from those of other parts of the world not only in the presence of many species or genera not known elsewhere, but also in the absence of some known to occur in European and other seas. This conclusion is based mainly on a study of the marine annelids, which have been remarkably abundant and diversified in many samples, and to a lesser extent on some other groups of invertebrates, especially amphipods and mollusks, which have been examined by authorities on these groups. Analyses are being made of more than 300 measured samples taken by the
Velero IV, research vessel of the University of Southern California. More than 283 species of polychaetous annelids have been identified. They have shown that there is a high degree of endemism, not only on specific, but also on generic levels.
