1021.] B. Prashad : Smnatyan Molluscs. 503 



have dealt with one of the species and here only include a few 

 notes on it. There are, however, in the collection a few specimens 

 of a species of the genus Contradens, Haas, a short account of 

 which is given below. 



Genus Monodontina, Conrad. 

 Monodontina vondembuschiana var. chapcri (de Morgan). 



igig. Monodontina vondembuschiana var. chapeyi. Prashad, Rec. Iini . 

 Mtis. XVI, pp. 407, 40S. 



In my recent paper I unfortunately missed a reference to one 

 of von Marten's papers' in which he had recorded a Sumatran 

 form under the name Pseudodon vondembiischiaims. Probably his 

 specimens also belonged to the variety chaperi. 



In the Sumatran collection the variety is represented by a 

 large series of specimens from the Soengei Kalau (a streamlet near 

 Bohorok), Soengei Deli at Medan and a few empty shells from 

 Bohorok. Mr. den Doop informs me that the empty shells had 

 been left there after the soft parts had been eaten. 



Genus Contradens, Haas. 



1913. Contradens, Haas, Nadir. Deiitsch. Malakosool. Ges. Xl,\ , 



P- .35- 

 igi^. Contradens, Haas, Mart. Cliemn. Conch. -Cab. Unio, p. 173. 



1914. Nodularia (in part), Simpson, Des. Cat. Naiades, p. 108. 



Haas proposed this genus on both shell-characters and soft- 

 parts for the species included by Simpson ' in his group of Nodula- 

 ria contradens. Simpson in his later work, cited above, has not 

 accepted Haas' new genus and continued his original scheme. 

 I have had a chance of examining the shells of some of the species 

 and the soft-parts of C. diniotus var. lugens recorded below, and 

 tliink that the genus is well characterised and should be separated 

 from Nodularia as accepted by Simpson. 



Contradens dimotus var. lugens (Drouet and Chaper). 



i,S(,2. Unio lugens, Drouet and Cli.'iper, Mem. Soc. Zool. France, V, 



^ p. 147, pi. V, figs. I-:,. 

 1914. Contradens dimotus lugens, Haas, op. cit., pp. 182, 183, pi. xix, 



fig. 7. 

 1914. Nodularia lugens, Simpson, op. cit., p. 1012. 



A large series of rather young shells from the Soengei Krah 

 at Medan, and a young specimen from a fresh- water area near 

 Medan, quite resemble Drouet and Chaper's description and 

 figures and also Haas' figure of one of the co-types. The only 

 differences are in the beaks being a little more high and having a 



absent (even in the chalky mountains) from the northern part of the government 

 " Oostkust van Sumatra" whereas they are abundantly represented in Sabang. 

 [den Doop], 



' Nachr. Deutsch. Malakozool. Ges. XXII, p. i,', (1900). 



2 Proc. U. S. Nat. Mus. XXI!, p. 817. 



