122 Rcxords (ij the Indian Museum. [Vol. XXII, 



Radii. A as in llie Bithyniinae but with the teeth relatively broader and the 

 laterals and marginals less differentiated , baso-lateral denticulations 

 present on the centrals. 



Soft parts. Fool long and narrow when expanded, spindle-shaped, point- 

 ed or produced behind, with the antero-lateral angles produced and the 

 anteiior margin excavate or truncate. Siioiif cylindrical, exti-emely 

 mobile and exf ensile. Tentacles filiform, bearing the eyes on slight promi- 

 nences at their base. Penis tvitlioiit a lateral process. 



The statements in italics in this description serve to differen- 

 tiate the subfamily. The small size of the shells causes them to 

 resemble those of the genus Hydrobia {Paludcstrina) superficially, 

 but their peculiar compressed form is most characteristic, while 

 the structure of the operculum and that of the central tooth of 

 the radula are different. With the Bithyniinae they agree in the 

 structure of the radula but not in other characters. 



The position of the subfamily, at least so far as the genus 

 Stenothyra is concerned, may now be discussed. Benson ' in 

 describing the genus did not assign it to any family or subfamily. 

 Woodward '^ included it amongst the Littorinidae as a subgenus of 

 Rissoa. Gray ^ followed Woodward in retaining Ncmatura in the 

 Littorinidae but differed from him in giving it a generic rank. 

 Adams * placed it among the Viviparidae and the same course was 

 adopted by von Frauenfeld.'' Troschel ' who still designated the 

 genus as Ncmatura placed it with Bythinia in his group Bythiniae, 

 Stimpson ' recognised its exact position more nearly, but guided by 

 both the shell and radular characters placed it in the subfamily 

 Hydrobiinae. Clessin,' after discussing the courses adopted bj- 

 previous authors, separated the subfamily Bythiniinae from the 

 Hydrobiinae, both of which he included in the family Rissoidae, 

 and placed the genus Stenothyra in the subfamily Bythiniinae. 

 Nevill, " following Adams and von Frauenfeld , assigned it to the 

 family Viviparidae or what he called the Paludinidae, while as to 

 its subfamily rank he agreed with Stimpson in including it amongst 

 the Bythiniinae. Fischer '° as already stated separated Stenothyra 

 with two fossil genera into a new subfamily of the Hydrobiidae- 

 Stenothj-rinae. Heude " placed the Chinese Stenothyra amongst 

 the Bithyniidae. The species from the Dutch East Indies were 

 assigned by von Martens '* to the family Paludinidae, but nothing 

 was said as to their subfamily rank. Fischer and Dautzenberg " 



' Benson, Journ. As. Soc. Bengal, V, p. 7S2 (18361, and Ann. Mag. Nat. 

 i/i'i^. XVIII, p. 496 (1856). 



■^ Woodward. RIanual of Mollusca, p. 137(11)51 — 1856). 



s Gray, Guide Syst. Dist. Moll. Brit. Mus. 1, p. 99 (1857). 



* Adams. H. and .\., Genera of Recent Mollusca I, p. .342 ^^s Nematiira (1858). 



6 von Frauenfeld, Verb. Zool.-bot. ges. Wien, XII, pp. 1157. 1158 (1862). 

 '' Troschcl, Gebiss der Schnecken 1, p. 104 (1856 — 1863). 



7 Stimpson, Smithsonian Misc. Pub. No. 201, p. 4" ('865). 

 i> Clessin, .Malakozool. Blatt. n. s. II, p. 193 (i8Su). 



"^ Nevill, Hand-List Moll. hid. Mus. U, p^ 42 i 1S8.S). 

 1" Fischer, Ma)!. Conchyliol. p. 724 11887). 

 il Heude, Mem. Hist. Nat. Chinois I. p. 173 (1880 — 1S90). 

 '2 von Martens. Suss-und Brack'.v.-Moll. in Zool. Ergeb. Nieder. Ost. In- 

 dien IV, p. 210 (1897). 



'3 F'ischer and Daut/enberg, Mission Pavie Indo-China, p. 420(1904'. 



