Mr. W. H. Benson on some forms 0/ Stenothyra. 499 



add to the information already possessed respecting this curious 

 little genus. I shall begin with the typical species — 



Stenothyra Delta y Benson. 



Testa vix rimata, globoso-conica, Iseviuscula, oblique exilissime striata, 

 striis obsoletis spiralibus minutissimis, versus basin remotioribus, 

 decussata, pallida fulva, albida, vel Gornea translueente ; spira co- 

 nica, acuminata, apice subtili, sutura impressa submarginata ; an- 

 fractibus 5|, superioribus convexis, sequentibus convexiusculis, 

 ultimo ventricoso, compresso, f testae sequante, antice descendente, 

 supra aperturam arcuatim striate, basi compresse rotundata ; aper- 

 tura obliqua, ovato-circulari, superne indentata, peristomatis mar- 

 gine dextro acutiusculo, columellari et basaU expausiusculis, pa- 

 rietali intus callo inconspicuo superne truncato, munito, extus sulco 

 impresso marginato ; operculo corneo, limbo albido. 



Long. 4-5, diam. 2^-3^ mill. 



Hab. in locis lutosis fluvii Hooghly prope Calcutta Bengalensem, 

 satis copiose ; necnon in lacu salso prope Balliaghat, ligno natanti 

 adhserentem ipse detexi. 



Syn. Nematura BeltcB, Bens. Journ. As. Soc. 1836, vol. v. p. 781 ; 

 Sow. Charlesw. Mag. 1837, vol. i. p. 217. 



I found it alive in both the places named ; also a dwarf variety 

 in an aqueduct, supplied by a steam-engine from the river, in 

 front of the Town Hall, at Calcutta. 



Stenothyra glabrata, A. Adams. 



Testa omnino imperforata, ovato-conica, laevissima, nitidissima, fusco- 

 cornea vel olivacea, spira coniea, apice acutiusculo, sutura impressa, 

 submarginata; anfractibus 5 convexiusculis, ultimo ventricosiori, 

 latere sinistro saepius gibbosulo, antice descendente, f testae 

 sequante, basi rotundata ; apertura obliqua, rotundato-ovata, su- 

 perne angulata, peristomate recto, obtuso, plerumque nigrescente. 

 Operculo typico, concaviusculo, fusco. 



Long. 3-51^, diam. 2-3;| mill. 



Hab. in paludibus Insulae Penang. Detexit Dr. Theo. Cantor. 



Syn. Nematura glabrata, A. Adams, Pr. Z. Soc. July 22, 1851 ; 



et var. olivacea, ejusdem, loc. cit. 

 Nematura polita, Bens. MSS., nee Sow. 



This shell, of which I have examined at least eighty speci- 

 mens, when divested of the reddish-brown earthy coating which 

 generally covers it, may be at once recognized, by its polish, 

 dark suite of colours, and freedom from sculpture and umbilical 

 rimation, independently of its form, which is more elongate than 

 the Gangetic species; also by the gibbosity of the left side of 

 the ventral volution, and the comparative absence of lateral 



3.2* 



