Other formats

    TEI XML file   ePub eBook file  


    mail icontwitter iconBlogspot iconrss icon

The Atoll of Funafuti, Ellice group : its zoology, botany, ethnology and general structure based on collections made by Charles Hedley of the Australian Museum, Sydney, N.S.W.

Diala virgata, sp. nov. — (Fig. 14)

Diala virgata, sp. nov.
(Fig. 14).

Shell imperforate, narrow, regularly conical, obtusely angled at the periphery, blunt at the tip, surface dull. Colour most variable, typically about half-a-dozen broad, irregular, opaque, white stripes extend longitudinally upon a translucent white ground from the suture to beyond the periphery of the last whorl, and cross the full breadth of the earlier ones. The translucent ground, but not the opaque patches, are crossed by an indefinite number, commonly page 423from eight to sixteen, spiral brown threads. These lines sometimes coalesce and produce a colour pattern of opaque white blotches on a dark chestnut ground. The opaque white spaces vary in number and extent; when re-stricted they appear as a series of rhombs on the periphery and triangles on the suture; by confluence these form longitudinal ragged stripes and separate the barred or brown tracts into rough ovals. This colouration is visible within the aperture. Sculpture— longitudinal growth lines are perceptible; the whole body whorl is evenly spaced by about a dozen, wide, very shallow grooves, upon the narrow in-tervening ridges of which are apt to occur the chestnut bars; the peripheral groove is the most distinct. Whorls seven, gradually increasing, slightly rounded; embryonic whorl one, minute, tur-binate. Suture deeply impressed. Aperture slightly oblique, ovate, pointed posteriorly, rounded and effuse anteriorly; colum-ella reflected, stained medially with chestnut; callus on body whorl slight, outer lip straight, simple. Operculum thin, corneous, ovate, paucispiral. Length 2¾,, breadth 1½ mm.

Fig. 14.

Fig. 14.

Very abundant; alive on stones and shells in shallow water in the lagoon.

This species differs from D. albugo, Watson, and D. ludens, Melvill and Standen, by a dull instead of a glossy surface, and by the opaque tracts occurring in larger continuous sheets instead of being scattered in small and numerous dots.

From the description of Rissoa fiammea, Pease,* I suppose that it is either the same or very like the shell before me.

* Pease — Am. Journ. Conch., iii., 1887 p.297, pl. xxiv., fig. 33.