38 COLLECTIONS EEOM MELANESIA. 



This is a more robust species than P. varicosa of Eeeve, is dif- 

 ferently coloured, has more prominent spiral ridges, a larger mimher 

 of costae, fewer swollen varices, and a more undulating duplex ridge 

 bordering the whorls above. These two, together with Drillia 

 tuherosa. Smith, from Japan, form a smaU group of species peculiar 

 on aocoimt of the varicose ribs which strengthen the shell at 

 intervals. 



5. Plexirotoma (Drillia) laterculata. (Plate IV. figs. E-E 1.) 

 Pleurotoma laterciilata, Sowerhy, Proc. Zool. Soc. 1870, p. 253. 



Hah. China Seas {Sowerhy) ; var. Port Molle, Queensland, 

 12-20 fms., rocky bottom {Goppinger). 



As the description given by Sowerby is altogether inadequate, I 

 herewith append a more detailed one drawn up from the type 

 specimen presented by Mrs. Lombe Taylor to the British Museum. 



Shell fusiform, whitish, much spotted and variegated with reddish 

 brown, principally between the longitudinal ribs, with a light violet 

 aperture. Whorls probably 11 ; two apical broken away ; the 

 rest very concave above, angulated at the middle, a little convex 

 beneath and contracted towards the suture, strengthened with 

 rather oblique costse (about 10 or 11 on the upper whorls), irre- 

 gularly continuous up the spire, somewhat obsolete in the concavity 

 of the whorls, which are also ornamented with two thread-like 

 pale lirae round the middle forming a kind of double angle, con- 

 tinuous between and upon the costse, where they become subacutely 

 prominent ; beneath these, in the penultimate and the antepenulti- 

 mate volutions, there is a third near the suture. Last whorl en- 

 circled with about thirteen similar pale lirse, besides interlying finer 

 ones, and several at the extremity which are very oblique. Canal 

 straight, feebly recurved, together with the aperture equalling less 

 than half the whole length of the shell. Columella perpendicular, 

 covered with a thin callosity, developed into a tubercle close to the 

 upper extremity of the outer Up. The latter is thin at the margin, 

 has a strong swollen varix behind, arcuately prominent at the 

 middle, with a well-marked sinus above in the concavity. Length 

 30 millim., width 10 ; aperture with canal 14 long. 



Variety. Shell of similar form and with the same sculpture, but 

 much less highly variegated. _ Of a dirty white colour, stained in 

 the concavity of the whorls "at the lower part next the suture and 

 round the miuaie of the last between the ribs with pale olive-brown. 

 Extremity of the body-whorl and the swollen varix suffused with a 

 reddish tint. Aperture pale lilac or whitish. The entire surface 

 of this species is seen, by the aid of a lens, to be striated with 

 minute spiral striae, crossed by lines of growth. The most striking 

 feature is the two white fine lirations at the middle of the whorls ■ 

 and although at times there may be one or two beneath them, none 

 appear to be found in the concavity above. The two apical whorls 

 are smooth, glossy, and convex. 



