174 Memoirs of the Indian Museum. [Vol. VII, 



The specimens of Dolium variegatum from the collections of the Indian Museum 

 hitherto studied were all of relatively moderate dimensions. Since the note above 

 alluded to was written, several more specimens have come to notice, unfortu- 

 nately of uncertain origin, remarkable for their large dimensions, and clearly corres- 

 ponding with the figured types of Dolium luteostoma and of the synonymous Dolium 

 japonicum, Dunker. At the same time, their specific identity with Dolium variegatum 

 does not admit of any doubt, and hereby is explained the occurrence of Dolium 

 luteostoma in the Arabian Sea as recorded by Melvill and Standen. It now remains 

 to be seen whether Dolium variegatum itself is to be treated as specifically identical 

 with Dolium galea, since the synonymous Dolium luteostoma is regarded by Melvill 

 and Standen as a mere variety of that species. 



With the exception of Küster, in his monograph of the genus Dolium published 

 in 1857 as part of the revised edition of Martini and Chemnitz' " Conchilien-Cabinet," 

 the authors who have dealt with these particular shells have only given short 

 diagnoses insufficient for identifying the various species. Even in the case of Küster' s 

 work, the excellent descriptions are mostly unaccompanied by comparative criteria. It 

 is therefore necessary to rely principally upon illustrations and upon actual specimens 

 for the discrimination of the species. With regard to the possible specific distinctness 

 of the forms variously described a D. galea, D. variegatum, and D. luteostoma, the 

 question is still further complicated by the necessity to take into account a Dolium 

 melanostoma, Jay (1839, Cat. Mus., p. 124, pi. viii-ix), with which D. luteostoma is 

 regarded by Try on (Manual of Conchology, Vol. VII, p. 261) as possibly identical. 



Apart from Melvill and Standen, in the above quoted reference, none of the 

 authors who have dealt with Dolium luteostoma appear to have had any hesitation 

 in considering it to differ specifically from Dolium galea, from which it is distinguished, 

 at the first glance, by its fewer and wider ribs. Tryon is the only author who has 

 thought it worth while to compare Dolium variegatum with Dolium galea and with 

 Dolium luteostoma and records, as the only distinction from the two species last 

 named, a relatively shallower suturai groove or rather depression, and a more elevated 

 spire for D. variegatum. 



It need scarcely be mentioned that differences of this kind, depending on mere 

 matters of degree and totally ignoring individual variation, are worthless from the 

 point of view of precise specific discrimination. I have vainly endeavoured, with the 

 material now available, to discover other distinguishing features. The degree of 

 elevation of the spire is extremely variable from one specimen to another, as is 

 obvious from the two specimens of Dolium variegatum figured in Reeve's monograph. 

 Of the two specimens of Dolium variegatum as interpreted by Küster, illustrated in 

 plate lxiii of his monograph, the larger one has so short a spire that it has unhesi- 

 tatingly been referred to Dolium, luteostoma by Tryon ; (the figure of the smaller 

 specimen being copied from Reeve). Moreover, the degree of elevation of the spire 

 may vary widely at different stages of growth even in the same specimen ; as in 

 the case of the larger of the two specimens figured by Reeve, and also in the case of 

 a very fine specimen in the collections of the Indian Museum, measuring 168 x 13g mm., 



