1919.] E. W. Vredenbfrg : Shells of the family Doliidœ. 175 



in which the suture becomes increasingly oblique with increasing growth, so that, at 

 earlier stages, the spire is extremely depressed, and gradually becomes more elevated 

 in the full-grown shell. In the case of such specimens, the earlier whorls exactly 

 agree with the diagnosis of Dolium luteostoma, the later ones with that of Dolium 

 variegatum. As to the sunken disposition of the suture in various individuals or in 

 various portions of one specimen, it is more or less pronounced inversely to the degree 

 of obliquity, but is always distinct. 



We may conclude that Dolium variegatum, Lamarck, and Dolium luteostoma, 

 Küster, undoubtedly represent the same species, which should be known by Lamarck's 

 designation which is older. 



The shell is undoubtedly very closely related to Dolium galea, Linn., though it 

 cannot be referred to the same species as has been done by Melvill and Standen who, 

 as already mentioned, have catalogued it from the Gulf of Oman as " Dolium galea 

 var. luteostomum." The spiral ribs, even taking full account of individual variations, 

 are always fewer in Dolium variegatum than in Dolium galea. At the largest stages 

 of growth, the number of main ribs, in Dolium variegatum, never exceeds nineteen, 

 and is usually less (frequently fifteen), while Dolium galea has at least twenty ribs 

 even in the case of small specimens, and usually more. There is also a very distinct 

 difference in the general shape of both species at all stages of growth, the convexity 

 of the body-whorl being more evenly continuous in Dolium variegatum than in Dolium 

 galea, in which latter species there is a decrease in the degree of curvature along the 

 zone of maximum width, communicating a slightly flattened appearance to the sides 

 of the shell. 



There remains to be considered the case of Dolium melanostoma, Jay, a remark- 

 ably handsome shell, the name of which refers to the dark colour pervading the 

 aperture, principally over the columellar lip. It seems to occur abundantly through- 

 out Polynesia and as far north as the Hawaiian Islands, but is not represented in the 

 collections of the Indian Museum. The two illustrations hitherto published, in the 

 works respectively of Jay (loc. cit.) and of Reeve (Monograph of the Genus Dolium, 

 species 2) are in every respect consistent with one another except as regards the 

 number of principal spiral ribs on the body-whorl, which amounts to twenty on the 

 specimen figured by Reeve, but which does not exceed fifteen in Jay's original type. 

 The number of ribs varies therefore approximately within the same limits as in the case 

 of Dolium variegatum, of which, judging by this character alone, Dolium melanostoma 

 might be merely a colour-variety. But there are other differences besides those of 

 colour. Judging from the apparently excellent illustrations, the outline of the spire 

 is more subulate, with less convex whorls than in Dolium variegatum. The sutures 

 are decidedly less sunken than in either Dolium galea or Dolium variegatum. The 

 absence of spiral ribs on the anterior winding terminal bulge of Dolium melanostoma 

 already noticed by Reeve as a good distinction from Dolium galea similarly distin- 

 guishes it from Dolium variegatum. The spire, in Jay's original type, is taller than 

 would seem ever to be the case with Dolium variegatum, while, in the specimen figured 

 by Reeve, it also exceeds the average of Dolium variegatum ; it is therefore probably 



