27 



DESCEIPTION OF SISTRUM OPABENSE, N.SP., FEOM THE 



SOUTH PACIFIC. 



r>y J. Cosmo Melvill, M.A., D.Sc. 



Read 8th December, 1911. 



SiSTKUM OpARENSE, 71. Sp. 



S. testa ovata, solida, versus apicem paullum attenuata, regulaiito. 

 spiraliter tuberculata, et minute transversim squamulata, anfractibus 

 5-6, quorum duo apicales in omnibus specirainibus liactenus visis 

 multum attriti, vel paitim fracti, albi, Ifeves, cseteris spiraliter 

 tuberculatis, tuberculis rotundis, regularibus, nitidis, ochraceis, 

 supernis duobus, ultimo anfractu quintis ordinibus decoratis, caetera 

 superticie transversim minute simul ac regulariter imbricato- 

 squamulata vel striata, apertura ovata, peristomate pallide lilacino, 

 labro intus 4-5 noduloso-dentato, margiiie columellari incrassato, 

 supra excavato, dein binoduloso, canali brevissimo, operculi nucleo 

 laterali. Long. 15, lat. 10 mm. 



Ilah. — Insula Rapa vel Opara, e grege Tubaiensi vel Australi, 

 Oceano Pacitico. 



I first noted tliis very attractive little species in tbe Shrewsbury 

 ' Museum, the specimens being gummed to a card, labelled on the 

 underside '■'■ Sistrum, sp , new?" presumably in the handwriting of 

 Mr. J. C. Lambert, whose well-selected general collection had lately 

 (1998) been presented to that institution. Upon my taking tliem 

 for comparison to the British Museum (Nat. Hist.), Mr. Edgar 

 Smith and I soon found corresponding examples, presented by 

 Mr. Lambert, with the fuller locality, as above recorded, given. The 

 species is allied to S. tuberculatum, Blainville, moms, LamU., etc., 

 but may be at once known by its much smaller size, regular symmetry, 

 and colour, of a pleasing ochraceous-chestnut, the tubercles being of 

 a slightly darker hue. Minute squamate striae, spirally arranged, 

 decorate the remainder of the surface ; the aperture and peristome are 

 very pale lavender in colour. In common with the majority of 

 authors who have recently added species to this genus,' I have 

 preferred continuing to employ the old Montfortian Sistriiin, 1810, 

 to the more unfamiliar Drupa of Bolten. Anyhow, if the genus be 

 considered subdivisible into two sections, whether Drupa, Bolten, 

 Pentad actylus, Klein, or Ricinula, Lamk., be used for the whole 



Vide Proc. Malac. Soc, vol. viii, pp. 17, 369, 1908-9. 



