(1) Two species of Folliculinidae are recorded from Cullercoats which have not been previously reported from Great Britain.

(2) The size, shape, and structure of Folliculinopsis producta Wright var. nov. elongata is somewhat different from the F. producta Wright described by various workers from the Continent and U.S.A.

(3) Fission, formation of larva, case secretion, and metamorphosis into adult have been described in F. producta Wright var. nov. elongata.

(4) Folliculina simplex Dons has the characteristic structure and life-history described by Faureć-Fremiet (1936). The mode of feeding in F. simplex has been recorded.

(5) It has been established that the extremely long tube of F. producta var. nov. elongata is single and is formed by one larva alone. In this variety it is not the result of an end to end arrangement of the secondary tubes of successive daughter individuals described by Andrews and Fauré-Fremiet in Folliciulinopsis producta Wright.

(6) It has been shown for the first time that the spiral ridge on the tube of F. producta is formed by a specialized spiral band of cilia on the neck of the larva.