498 Records oj the Indian Museum. [Vol. XXII 



Measurements of shells {in niillimetres). 



A (Type). B. 



Maximum diameter ... ... 14-3 13-7 



Heiyht ... ... 6 59 



Height of aperture ... ... 10 g-8 



Columellar plate ... .. 7-4 6'^ 



Locality. — The two specimens of this species were collected 

 by Mr. den Doop from near the mouth of the Soengei Eatang 

 Kwis (Serdarg), in the mangrove swamp region. 



Remarks. — The species is closely tdlied to N . auriailata. Lam., 

 but differs from it in the shell being more elongate, the auricles 

 much less developed and in the comparatively greater width of 

 the columellar plate. The species is interesliiig in that it affords 

 a connecting link between the subgenera Neripteron and DosHa. 



I have associated the name of this species with that of Mssrs. 

 Simon (Managers of the Estates Batang Kwis and Loeboe Pakam) 

 who greatly assisted Mr. den Doop in making collections on their 

 estates. 



Subgenus Dostia, Gray. 



1879. Dostia. V. Martens, Nerltina in Mart, and Clieniii, Condi. -Cab.. 



pp. 16. 37. 

 1883. Dostia, Tapparone-Canefri, A7111. M;is. Civ. Stay. Nat. Geno-va. 



XIX, p. 63. 

 1919. Dostia, Annandale and Prashad, Rec. Ind. Miis. XVI, pp. 241, 



242. 



In the paper cited above Dr. Annandale and I considered 

 Dostia to be sufficiently well characterized to deserve generic 

 rank. Having since examined the large collections in the Indian 

 ^luseum, some Mesopotamian shells, and the large Sumatran 

 collection I find that there are various intermediate forms between 

 it and the subgenus Neripteron. Dostia, therefore, cannot stand as 

 a separate genus but must be considered as a subgenus of Neritina. 

 Von Martens' name " Neritae Mitrulae " must, however, give way 

 to Gray's older name Dostia. 



Neritina crcpidularia, Lam. 



1879. Neritina crepiii iil aria, V. Martens, op. cit., pp. .,7-45, pi. vii. 



fi.afs. 1-4. 

 1897. Neritina crepidiilaria ivitli var. inelanostonia, v. Marten^, op. 



rif., p. 21S. 



This widely distributed species is represented in the Suma- 

 tran collection by two varieties, which are separately considered 

 below. 



var. melanostoma (Troschel). 



1837. Neritina melanostoma, Troschel, Arch. Naturgesch., p. 179. 



This variety was described from specimens collected in the 

 River Ganges, probably from the deltaic region. It is represented 

 from Sumatra by a large number of specimens of all ages collected 

 in the mangrove-swamps at Belawan (Deli). The Sumatran speci- 

 mens are exactly like the Indian shells. 



