Abstract
S. fiordicum and S. holmei appear to be closely related. The distinction between the two is to be found in the “zone of thickened papillae” and the postannular region. As the hind end (anchor) is unknown for S. holmei the question as to whether these two species should be classified as a single species cannot at this juncture be contemplated. The bridle is considered as the tool by means of which the animal smears the exudate onto the inner surface of the tube. The larvae of S. fiordicum develop the bridle before they leave the maternal tube. The larval dorsal ciliary field divides into an anterior region which is lost in the adult, and a posterior region which is retained as the dorsal ciliary field of the metameric region.

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