1920.] NATURAL SCIENCES OF PHILADELPHIA. • 199 



wider intervals, a narrow plain band below the suture and a wider 

 one within the umbilicus. The aperture is slightly oblique, rounded- 

 oval, the peristome very shortly adnate in adults (or sometimes 

 very shortly free, continuous). 

 Alt. 0.75, diam. 1.75 mm. 



Fig. 4. — Cochliopa hinkleyi. 



Lake Izabal near Jocolo, Guatemala, A. A. Hinkley. 



With the sculpture of C. guatemalensis, this species has the shape 

 of a small Planorbis of the parvus group. In most adult shells the 

 inner whorls are eroded away, leaving a hole through the center of 

 the disc, as in the right hand figure. Sometimes the last whorl is 

 shortly free, as in the lower figm-e. 



Cochliopa minor new species. Fig. 5. 



The shell is depressed, umbilicate (the umbilicus rapidl}^ enlarging 

 in the last whorl, contained five times in the diameter), soHd, very 

 pale brownish. The spire is very low conic. The first of the four 

 whorls is smooth ; spiral ridges set in on the second ; on the last there 

 arc about 23 of these ridges, nearly equal, and a little narrow^er 

 than the concave intervals; the latter showing microscopic growth- 

 lines and traces of fine spirals in some places. The last whorl is 

 rounded peripherally, and descends slightly to the aperture. Aper- 

 ture is strongly oblique, rounded. Peristome blunt, the margins 

 joined by a heavy parietal callus. 



Alt. 1.2, diam. 2.1 mm.; 4 whorls. 



Cochliopa minor. 



Polvon, Nicaragua. Type and paratypes No. 58,286, A. N. S. P., 

 collected by the McNeil Expedition. 



