DISTRI.BUTION OF OLIGOCHAETES IN WESTERN

A total of 52,390 oligochaetes were collected from 40 stations in western Lake Erie in spring 1961. The population was composed of two families, Naididae and Tubificidae. Only six species of naidids were found. One, Paranais frici, is apparently new to the list of North American freshwater Naididae. Among the 14 tubificids found, five species of Limnodrilus were most abundant; they contributed 90 % or more of all oligochaetes at 33 of the 40 stations. Numbers of Limnodrilus were generally large near the mouths of the Detroit, Raisin, and Maumee rivers and decreased progressively lakeward. Stylodrilus heringianus, a pollution-intolerant species common in eastern Lake Erie, was not found in the western end of the lake