This generic name was used in different ways by authors in the past, mainly because its type species cannot be identified unequivocally. There seems to be no type specimen left. The original diagnosis is as follows (A. Adams, 1860: 405): "Testa subulata, recta, vitrea, polita; anfractibus planis; suturis impressis. Apertura oblonga; labio in medio plica obliqua instructo; labro simplici, acuto.
This genus bears the same relation to Obeliscus [e.g. Pyramidella Lamarck,1799] that Chrysallida does to Pyramidella [e.g. Otopleura Fischer, 1885], and will include all the slender species of the former group with a single plait on the columella. It differs from Monoptygma [e.g. Adelactaeon Cossmann, 1895] in being vitreous and polished, and from Odostomia in texture and in its subulate or aciculate form".
From this text we deduce that the species of this genus should have smooth, slender shells with a clearly defined tooth on the columella. Whether this combination of characters defines a natural entity is unknown. Pending further study, we do not agree with Penas & Rolan (1999a: 131,134), who include Eulimella endolamellata Schander, 1994, and E. vanhareni van Aartsen et al., 1998, in Syrnola. In shells of these two species there is only a fold, not a tooth on the columella.

Shell slender and narrowly tapered, smooth and shining, with almost straight-sided whorls. The protoconch is heterostrophic, of helicoid coiling, with the nucleus small, lateral and central, and there is a strong columellar fold.
New Zealand range, Oligocene to Recent.

Typically elongated shells with flattened whorls, smooth and porcellanous in texture, often coloured or with brown bands; the protoconch exsert and tilted heterotrophe; the columella fold single, generally prominent, but occasionally nearly obsolete and only visible inside the aperture.