1919.] E. W. Vredenburg : Shells of the family Doliidce. 177 



height of no mm., not disproportionately greater therefore than the largest previously 

 known specimens of Dolium chinense. In addition to its large size, it is considered to 

 be further differentiated by the character of its spiral threads, said to be flatter than 

 in Dolium chinense. At all stages of growth, Dolium chinense is always characterised 

 by its relatively flat ribs, this feature constituting a good distinction from Dolium, 

 variegatum, with which it has been erroneously united by Philippi and by Tryon. The 

 collection of the Indian Museum includes a specimen, unfortunately of unknown 

 origin, measuring 115 x 98 mm., even larger therefore than G. B. Sowerby's type of 

 Dolium magnificum, with which it otherwise corresponds in every respect. The ribs 

 of the body-whorl, as in the case of Sowerby's type, are still flatter than in specimens 

 of Dolium chinense of moderate size ; the ornamentation, indeed, consisting of linear 

 grooves rather than ribs. Yet, the spire-whorls plainly show that, at earlier 

 stages of growth, the ribs are less flattened and are disposed exactly as in typical 

 specimens of Dolium chinense. The protoconch of the specimen corresponding with 

 Dolium magnificum is of exactly the same size and shape as in typical specimens 

 of Dolium chinense ; indeed, all the earlier portion of the spire is absolutely undistin- 

 guishable. The paired disposition of the maculated ribs observed in the type of 

 Dolium magnificum, and in the corresponding Calcutta specimen, is frequently matched 

 amongst typical specimens of Dolium chinense. It seems obvious that Dolium magni- 

 ficum is specifically identical with Dolium chinense, of which it represents a full-grown 

 stage. 



Even these exceptionally large specimens of Dolium chinense do not nearly 

 approach the maximum dimensions of Dolium variegatum, which reaches as much as 

 230 mm., and ranks amongst the largest known gastropods. Dolium chinense is there- 

 fore well distinguished from Dolium variegatum by its smaller average size, its feebly 

 sunken sutures, and its more crowded and flatter ribs, the difference becoming 

 especially marked in large specimens of both species, since, in the case of Dolium 

 variegatum, there is no indication, with increase of size, of the extreme flattening 

 characterising the full-grown stage of Dolium chinense. 



IV. — List of the Doliidce in the collection of the Indian Museum. 



While engaged upon the study of the tertiary fossil Doliidse in the collections of 

 the Geological Survey of India, I had occasion to examine, for purposes of com- 

 parison, the rich series of recent shells of this family in the zoological collections of 

 the Indian Museum. Many of these valuable specimens had remained unnamed, and, 

 as the work of comparison necessitated the identification of the recent as well as of 

 the fossil specimens, advantage may be taken of the present opportunity to place on 

 record the contents of the collection of recent shells, all the more so as, in the ma- 

 jority of cases, we possess precise details as to the locality from which the specimens 

 were obtained ; the information thus obtainable supplementing in several instances 

 that previously published. 



According to the classification schemes of Fischer {Manuel de Conchyliologie, 



