19-21.] B. Prashad : Siimatran Molluscs. 493 



forms dealt with here. None of the specimens belong to the typi- 

 cal form. 



var. nodosocostata (Moiisson). 



The specimens of this variety are from a pool in the valley of 

 the Lau Kling (a stream) near Brastagei and from the Soengei 

 Bohorok. The costae on young individuals are rather faint and 

 the body-whorl is nearly smooth. 



var. angulifera, v. Martens. 



The only specimens of this form were collected in the 

 streamlet Soengei Kalau (near Bohorok). They agree in all res- 

 pects with one of von Martens' co-types from Rotti, nver Oilelao, 

 near Bilba, in the Indian Museum collection. 



var. mutica, v. Martens. 



This form is represented in the Sumatran collection by a 

 fair number of specimens from a streamlet near Anak Laut (Sa- 

 hang). 



Subgenus Tarebia, H. and A. Adams 



Melanoides semigranosa (Busch). 



1842. Melania semigranosa, \'. V>. Busch, Philippi Abbild. I. p. 2, pi. 



i, fig- 13- 

 1874. Melania lirata var. 2, Brot, op. cit., p. 329, pi. xxxiii, figs. 6,6a. 

 1885. Melania lineata var. semigranosa, Nevill, op. cit., p. 277. 

 1897. Melanin lineata var. semigi'anosa, v. Martens, op. cit., p. 72. 

 1899. Melania (Tarebia) semigranosa, Dautzenberg, A}tn Soc. Roy. 



Malacol. Belgique. XXXIV, p. 14, pi. ii, figs. 9, qa-c. 



I agree with Dautzenberg in considering this form as a dis- 

 tinct species rather than as a variety of M. lineata. The specific 

 characters as defined by Mousson are, as was also found by Daut- 

 zenberg, quite constant in a large series of specimens. 



The specimens in the Sumatran collection are from the Soen- 

 gei I^epan, the Soengei Kalau and from Medan. 



Family Cerithiidae. 



Genus Potamides, Defr. 



This genus is represented in the collection by specimens of 

 the three subgenera, Telcscopiitiii, Montf., Tympanotonos (Morch) 

 Adams, and Ceriiliidea, Swains. There are no specimens of the 

 subgenus Pyrazns, Montf ., which is also known from Sumatra. 



Subgenus Telcscopium, Montf. 

 Potamidcs telescopium (Linn.). 



1855. Cerithinm telsecopi:im, howerby, Theasanrtis Concliyliorum, 11, 



p. 890, pi. clxxxv, fig. 269. 

 1866, Telescopium fuscitm. Reeve, Conch. Icon. X\'. pi. i, sp, I, a b. 



