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

108 COLLECTIONS FROM MELANESIA,This so-called species, also C. donacina, Lamarck, 0. ciimmgii, A.Adams, 0. castanea, Reeve, C. errones, Reeve, and O. decipiens,Reeve, I believe to be mere variations of one and the same form,namely C. Jcimpcola, Lamarck, The composition of the hinge is thesame in all, and the peculiar colouring of the interior is similar (videReeve, fig. 16, and Delessert, pi, iv. fig, 1 b). The variation in formis partly due to age ; for instance, a young 0. decipiens has the formof donacina, and it is only towards maturity that the posterior endbecomes markedly produced ; and the same observation applies to G.errones. The amount of concentric ribbing is not constant ; but allintermediate forms are met with, from 0. castanea and C. donacina(type), which have least, to 0. pidchra, which has most, being costatethroughout, except at the posterior extremity. The pallial linein every specimen examined does not appear to be parallel with themargin of the valve, but becomes gradually more remote anteriorly,the space between it and the margin being radiately shallowlysubsulcate, seen better in some lights than others. The epidermisscarcely varies at all : in some examples it appears to have lost thedull bloom which covers others ; but this defect is the result of friction,for a dull specimen in perfect condition is easily renderedglossy by merely being rubbed with a wet cloth, the bloom disappearingas it does from fruit under similar circumstances. Judgingfrom the specimens in the British Museum with reliable localitiesattached to them, it appears that the species ranges from Queenslandon the east side of Australia, along the north coast to Swan River onthe west, I find a specimen of the variety cmningii from PortCurtis and another from Sandy Cape on the north-east coast ; var.ptdcJira from Port Essington; vars. decipiens and castanea fromSwan River.50. Modiola, sp.Hah. Port Molle.A single distorted specimen only is before me, remarkably likethe European M. barbata.51. Modiola glaberrima.Dunher ; Reeve, Conch. Icon. fig. 48.Hcd). Sydney {Dunher) ; Port Jackson (Coppinger and Angus).52. Modiolaria miranda. (Plate VII. fig. N.)Shell transversely elongate, highest at the middle, of pale greenishtint, varied with a few indistinct light reddish irregular markings,not glossy, rather strongly radiately ridged at both ends and veryfinely on the central portion of the valves. Whole surface concentricallystriated, producing a subgranose appearance upon the costulse; the anterior are about ten in number, the posterior about