Report on the zoological collections made in the Indo-Pacific Ocean ...

:38 COLLECTIONS FROM MELANESIA.This is a more robust species than P. varicosa of Reeve, is differentlycoloured, has more prominent spiral ridges, a larger numberof costaj, fewer swollen varices, and a more undulating duplex ridgebordering the whorls above. These two, together with Drilliatiiberosa, Smith, from Japan, form a small group of species peculiaron account of the varicose ribs which strengthen the shell atintervals.*5. Pleurotoma (Drillia) laterculata. (Plate IV. figs. E-E 1.)Pleurotoma laterculata, Sotverby, Proc. Zool. Soc. 1870, p. 253.Hab. China Seas (Soiverby) ; var. Port Molle, Queensland,12-20 fms., rocky bottom {Goppinger).As the description given by Sowerby is altogether inadequate, Iherewith append a more detailed one drawn up from the typespecimen presented by Mrs. Lombc Taylor to the British Museum.Shell fusiform, whitish, much spotted and variegated with reddishbrown, principally between the longitudinal ribs, with a light violetaperture. Whorls probably 11 ; two apical broken away ; therest verj;- concave above, angulated at the middle, a little convexbeneath and contracted towards the suture, strengthened withrather oblique costse (about 10 or 11 on the upper whorls), irregularlycontinuous up the spire, somewhat obsolete in the concavityof the whorls, which are also ornamented with two thread-likepale lirae round the middle forming a kind of double angle, continuousbetween and upon the costce, where they become subacutelyprominent ; beneath these, in the penultimate and the antepenultimatevolutions, there is a third near the suture. Last whorl encircledwith a]iout thirteen similar pale liroe, besides intcrlying finerones, and several at the extremity which are very oblique. Canalstraight, feebly recurved, together with the aperture equalling lessthan half the whole length of the shell. Columella perpendicular,covered with a thin callosity, developed into a tubercle close to theupper extremity of the outer lip. The latter is thin at the margin,has a strong swollen varix behind, arcuately prominent at themiddle, with a well-marked sinus above in the concavity. Length80 millim., width 10 ; aperture with canal 14 long.Variety. Shell of similar form and with the same sculpture, butmuch less highly variegated. Of a dirty white colour, stained inthe concavity of the whorls at the lower part next the suture andround the middle of the last between the ribs with pale olive-brown.Extremity of the body-whorl and the swollen varix suff'used with areddish tint. Aperture pale lilac or whitish. The entire surfaceof this species is seen, by the aid of a lens, to be striated withminute spiral stri?e, crossed by lines of growth. The most strikingfeature is the two white fine lirations at the middle of the whorlsand although at times there may be one or two beneath them, noneappear to be found in the concavity above. The two apical whorlsare smooth, glossy, and convex.