Contents

Taxonomy.

Serpulorbis zelandicus, S. aotcaroa n.sp., Novastoa lamellosa.

Serpulorbis zelandicus.

Discussion.

Summary.

References to Literature.

The Vermetidae are at present one of the least satisfactorily known of gastropod families. The shell is typically spiral in the embryo, but at an early stage the spire loosens, becoming finally wholly or partially uncoiled and often irregularly twisted, either embedded in or cemented to the substratum. Adult shell characters are unreliable in classification and the group holds no delights for the conchologist: a natural arrangement depends principally on the structure of the animal, which is intimately adapted to the specialised mode of life. It is now proposed to consider the structure of the New Zealand representatives of the Vermetidae from the functional aspect, as a contribution to the classification of the family.

The principal literature dealing with the vermetid animal consists of the early memoir of Lacaze-Duthiers (1860) on the anatomy and embryology of “Vermetus” triqueter and “Vermetus” semisurrectus; a short account by Rougement (1880) recording the mode of feeding of “Vermetus” gigas; and in more recent times three papers on the biology of the Vermetus group—Boettger (1930) on V. gigas, Yonge (1932) followed by Yonge and Iles (1939) comparing V. novae-hollandiae and V. gigas.

Powell's check-list of the New Zealand recent mollusca (1946) includes two species assigned to the genus Vermicularia—sipho (Lamarck, 1818) and maoriana (Powell, 1937). The latter is a deep-water Aupourian form, known at present only from the type shell; as its author points out, the generic location in Vermicularia is to be regarded as merely provisional. The New Zealand species associated with the Australian sipho may be conveniently restored to Serpulorbis as in Suter's Manual (1913); Finlay (1927), in following Hedley's removal of these shells to Vermicularia, had no material of the animal available. As defined by Thiele (1931) Vermicularia is not appropriate for sipho; that genus is best reserved for vermetids with the “shell not

attached, at first coiled like Turrietella, later irregularly extended.” Moreover, there is an “operculum as large as the aperture.” Serpulorbis is distinguished in being firmly attached along one side to the substratum, and irregularly uncoiled from the outset. The operculum is always absent as in sipho.