I^d3.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 257 

 ^— - ^ = 



VoL Till, ]¥o. 17. l¥:)!^hE&igto», ©. C. J«Bly 13, 1885. 



])art a little flexuoiis, aperture rounded behind or not angular, inner 

 lip somewhat arched ; umbilicus small ; apex rounded ; opercnlum dark 

 brown, subspiral, longitudinally spirally striate iuside; animal whitish 

 marbled with l»lack or djirk gray ; eyes large, black; tentacles moderate, 

 blunt at tlic tip; a wliitish streak behind them; foot bluish white, 

 mr.zzle dark, with an indentation in the median line; dentition much 

 like th;it of B. n'tcldiniana Lea, the rhachidian tooth proportionately 

 wider and larger; the first denticle on the inner edge of the cusj) of 

 the tlrst lateral tooth large and prominent, and the tips of the outer 

 laterals with one or two well-marked denticulations. Lon. of shell 3.0 

 to 4.8"""; max. lat. 2.0 to 3.0™"; aperture from a little more than one- 

 third to a little less than one-half as long as the shell. 



Hahitat. — Brook flowing from Benson's mineral spring into Lake Mon- 

 roe, at Enterprise, Fla. 



This shell resembles closely the stouter specimens of Pomatlopsis lus- 

 trica Say, but is less acutely pointed and has one whorl less ; the soft 

 l)arts, on the other hand, are like those of BythinelJa nickliniana Lea. 

 There is reason to believe that it is identical with the species described 

 by Frauenfeld as above mentioned, probably from the same locality, in 

 jNIus. Cuming. It was also collected near Lake Monroe by Shuttle- 

 worth, whose specimens are in the Imperial Museum at Vienna. This 

 and several other American species described from Shuttle worth's col- 

 lections bj" Frauenfeld seem to have escaped the notice of American 

 writers on the Eydrohiincc* There is a noticeable difference in form, 

 indicated in the measurements above, among the specimens collected by 

 me, which seems to be sexual. Unlike Stimpson, 1 found the stout ones 

 to be invariably females. Everj^ grade, however, existed between the 

 XQry stout and the most elongated. They were found on floating wood 

 and leaves of plants in quiet places in the little shallow brook associated 

 wi^h Limncva coliimella, Ancylus and Planorhis, exclusively underwater. 

 Amnicola floridaiia Frauenfeld. 



Amnicola Jioridana Frauenfeld, 1. c, 1863, p. 1028 et 1865, p. 529, \)\. x, fig. 4, a-h. 



BylhineUa obtusa Lea, Dall. Proc.U. S. Nat. Mus., 1883, p. 334. 



Owing to misinformation, I was led, in my paper on Hemphill's shells 

 in 1883, to place the above species (whose generic place is still unsettled) 



" HydroMa corrigata Frauenfeld, 1. c, pp. 1021-2, received from Boston, Mass., 

 under the name of Cingula minufa Totteu, but according to Frauenfeld not that spe- 

 cies. It is further refeiTed to and figured, 1. c, 1865, pp. 525-6, pi. viii, fig. 3, a-1). 

 Hyclrohia Seemani Frauenfeld, 1. c., p. 1025, 1863, p. 525, 1865, pi. viii, fig. 1, a-h, is 

 recorded as collected in Northwest Mexico, Durango, by Seemaun, and the types are iu 

 Mu.s. Cuming. Amnicola Schrdldngeri Frauenfeld, 1. c, 1863, p. 1030, and 1865, p. 528, 

 pi. X, fig. 2, a-h, is described from Massachusetts specimens named '^luslrica Saj'-," 

 iu Mus. Cuming. Amnicola ciDcinnatiensis Anthony, is mentioned as being the Palu- 

 dina fniticatella Ziegler MS. from New Orleans, in Mus. Cuming. Others are referred 

 to elsewhere iu the present paper. 



Proc. Kat. Mus. 85- 17 



