1906.] NATURAL SCIENCES OF PHILADELPHIA. 173 



whorl at the aperture shows it to be adult. Five specimens were taken. 

 The shells are all more or less bleached, the freshest being of a pale 

 corneous tint. The round whorls, deep suture and general appear- 

 ance are quite unlike any Planorbis or Vallonia, and indicate, we think, 

 either that it is a Valvata or an Amnicoloid snail comparable to Horatia 

 Bgt. or Daudehardiella Bttg. in the Paltearctic fauna. Until fresh 

 specimens with the soft parts or operculum are found, the position of 

 this molluscan atom will remain uncertain. 



Valvata micra nugax (pi. IX, fig. 6), a slightly larger form, alt. .9 

 diam. 1.5 mm., with three whorls and a projecting spire, may prove to 

 be a distinct species; but for the present, until more specimens are 

 found, it may be placed under T^. micra as a variety or form. 



CYRENIDu^]. 

 Pisidium singleyi Sterki. 



Nautilus, XI, 1S9S, p. 112 (type loc. Guadalupe river, Comal county, Texas). 



Drift debris of Guadalupe river about four miles above New Braun- 

 fcls, and of Devil's river, \'al Verde county, Texas. A closely related 

 form was found near Del Rio. 

 Pisidium compressum Prime. 



New Braunfels, Comal county, Texas. Mr. J. A. Singley found P. 

 trapezoideum Sterki at the same place (coll. A. N. S. Phila. No. 60,127). 

 Pisidium abditum huachucanum n. subsp. 



The shell is quite inflated, dark brownish-olive, irregularly striate 

 and marked with several conspicuous dark growth-arrest streaks; 

 very inequilateral, the beaks low and near the anterior end. Anterior 

 end abruptly truncate, posterior end produced and rounded. Hinge 

 rather narrow, the lateral teeth in the right valve single, short and 

 high, triangular ; in the left double. Length 5. 1 , alt. 4.3, diam. 3.4 mm. 



Stream in Carr canyon, Reef, Cochise county, Arizona, collected by 

 C. R. Biedermann, February 8, 1904. 



Specimens were submitted to Dr. V. Sterki, who could not identify 

 the form with any known species. About half of the shells are more 

 compressed than those described as typical, one measuring, length 4.1, 

 alt. 3.4, diam. 2 mm. The very inequilateral, anteriorly truncate out- 

 line and low beaks are characteristic of both the obese and com- 

 pressed forms. 



Eupera singleyi (Pils.). 



Sphoerium {Limosina) dngleyi Pils., Proc. A. N. S. Phila., 1889, p. 88, pi. 



3, figs. 14, 1.5 (May 14, 1889). 

 iCyclas macvJata Morelet, 1859, not of Anton, 1839 =Sphoerium yacatanense 

 Fischer and Crosse, Miss. Sci. Mex., Moll., II, p. 653 (1894). 



This species is now known to us by specimens from the following 



