492 Records of iJic Indian Museiun. [\'oi,. XXII, 



var. seminuda, v. Martens. 



189;. Melanin tiibefcidata var. seminuda. v. Martens, of>. cit., p. 58, 

 pi. iv, tig. I . 



Von Martens recorded this variety from a number of localities 

 in Sumatra and in the present collection it is represented from 

 the following sources : — Fresh-water areas at Medan and Toentoen- 

 gan, streamlets at Sahang and Timbang Langkat, the Soeugei 

 Landak and Soengei Bohorok (both near Bohorok). 



Some of the specimens, owing to a deposit on the surface, 

 appear much darker than others. 



var. virgulata (Quoy and Gaim.). 



1897. Melaiiia tuberciilata \ar. virgulata, v. Martens, op. cit., pp. 57, 



58. 



This variety is widely distributed in the Malay Archipelago, 



and has been recorded from various localities in Sumatra. In the 



present collection there are specimens from a fresh-water area at 



Medan and Padang Boelan and from the Soengei Bohorok. 



var. angularis, v. Martens. 



1867. Melanin tuberculata var. angularis. v. Martens, op. cit., p. 59. 

 pi. iv, fio-s. 2, 3. 



This form is only known from Sumatra. I have compared my 

 specimens with one of von IMartens' co-types and have no doubt 

 as to their identit5^ 



The specimens are from near Medan, from a streamlet on the 

 Medan Estate, from the Soengei Bohorok and Anak Laut (Sabang). 



var. truncatula (Lam.). 



1897. Melania tuberculata var. truncatula, v. Martens, op. cit., p. 59' 

 pi. iv, fig. 4. 



Large series of specimens of this interesting form are repre- 

 sented in the Sumatran collection from Padang Boelan, Poengei, 

 Medan and Timbang Langkat, and from the Soengei Bohorok and 

 Soengei Minahol. 



The ribs in fully adult specimens become greatly reduced and 

 are not so clear as they are on young shells. 



Melanoides scabra (Miill.). 



1S97. Melania scabra, v. Martens, op. cit., p. 62. 



The groups or subgenera Plotia and Striatella as defined by 

 Brot in his monograph, as has been pointed out by Dr. Annandale 

 and mj'self,' fade imperceptibly into one another and we have, 

 therefore, adopted the older name Plotia for the subgenas. 



The complete synonymy of M. scabra and its allies has still to 

 be worked out,' but there is no doubt regarding the Sumatran 



' Rec. Ind. Mus. XVllJ, p. 28 (1919), see also Vol. XIV, p. 147 (1919)- 

 * Rec. Ind. Mus. XVIII, p. 37 (igig). 



