193 



columella arcuata, involute, tubulum efformante. Long. 1-Jg- ; lat. ^ 

 poll. 



Allied to A. octona, decollata, &c. 



Pupa [Ennea] pumilio. T. obovata, ventricosa, sursum acuta, 

 apice rotundata, imperforate, albida, nitida, : anfractibus 7 planulatis, 

 leviter striatis, ultimo deorsum attenuato ; sutura lineari ; apertura 

 parva, semi-elliptica, lamella, unica, postica cum labro continua, et 

 plica umbilicali angulata impedita ; peritremate albo, undulato, leviter 

 et inequaliter reflexo. Long. -|-| ; lat. ^ poll. 



Pupa [Ennea] capitata. T. cylindracea, apice rotundata, albida, 

 imperforata ; anfractibus planulatis, concinne oblique striatis, ultimo 

 deorsum attenuate, basi carinata, externe et sub sutura umbilicali 

 indentata ; sutura eonspicua ; apertura angusta, protensa, subovali, 

 basi sub-angulata, lamella postica, altera columellari, dentibus quatuor 

 inequalibus, plicaque umbilicali dentifera ringente ; peritremate Can- 

 dida, reflexa. Long. ^1 ; lat. ^ poll. 



Melania mutans [is M. fuscata, Gmel., which varies greatly in 

 its exterior sculpture]. 



Anodonta Salweniana. T. trapezoidea, compressa, subtenui, 

 retro dilatata, postice truncata, colore picca ; supra costam umbona- 

 lem radiatim plicata, : umbonibus parum elevatis ; margine superiori 

 recta, compressa, ligamentum occultante, ante umbonibus excavata ; 

 utraque valvii processu dentiformi cardinali, uno ante altero aptante, 

 instructa ; cavositate minime profunda ; impressionibus muscularibus 

 minimc impressis; margarita sub-Uvida. Long. 51; lat. I 1 -; alt. 2i- 

 poll. River Salwen, British Burmah, Rev. F. Mason. 



Resembles small specimens of Alas, complanata, but is much less 

 ponderous. 



A. inoscularis. T. transverse oblonga, sub-ovata, solida, subven- 

 tricosa, picea : umbonibus parum elevatis ; margine supra brevi, recto, 

 ad angulum posticum rotundato, postice subtruncato ; infra arcuata ; 

 utraque valva processu cardinali crassa, dentiformi, instructa, uno 

 ante altero aptante ; margarita albida ; hnpressione musculari antico 

 profundo. Long. 3; lat. 1|; alt. ll poll. River Salwen, Rev. F. 

 Mason. 



Very closely allied to A. edentula, Say, but is a more solid shell, 

 and the cardinal ajiophyses are more elevated and stronger. 



D^= Vol. i. 161, May, 1844. 



The prominent tooth-like apophyses of these shells, render their 



position among the genera of Naiades, as now received, somewhat 



equivocal ; uniting, as they do, Alasmodon and Anodon ; and they 



strengthen the idea entertained by many, that the modifications in 



25 



