Abstract
C. kozloffi sp. nov. is described from the intestine of the sipunculan T. dyscrita, collected at 3 localities on the Oregon [USA] coast. This species is particularly distinctive because of its large egg capsule (length about 400-500 .mu.m). The relationships of the other known species of Collastoma [C. eremitae, C. monorchis, C. pacifica and C. minutum] are discussed.