2 University of Michigan 



by a deeply impressed suture, body whorl large, ventricose 

 and regularly rounded ; aperture large, broadly rounded nearly 

 circular from the upper insertion of the lip to the base of the 

 columella; lip sharp, slightly thickened within, giving a bev- 

 eled appearance to the inner margin, continuous, but slightly 

 adnate to the body-whorl between the umbilicus and the upper 

 insertion of the lip, but its curve is not impinged upon by the 

 body-whorl, umbilicus fairly wide. 



Alt. 3.75, diam. 2.75, aperture alt. 2 mm. 



Reservoir north of Guatemala City, Guatemala. 



Types Xo. 47161 Coll. \\'alker. Cotypes in the collections 

 of A. A. Hinkley, the Philadelphia Academy and the ]\luseum 

 of Zoology, Univ. of Mich. 



This well marked species is evidently related to Amnicola ■ 

 stolli v. IMts., which was found in a very similar situation, i. e., 

 wells in the town of Antigua, Guatemala, but dififers in being 

 larger and more ventricose and in the larger and broadly 

 rounded aperture. In stolli, according to the figure, although 

 it is not mentioned in the very brief description, the body- 

 whorl is apparently obsoletely angled at the periphery and the 

 aperture is distinctly angled above owing to the flattening of 

 the upper portion of the lip; whereas in cistcniina the body- 

 whorl is regularly rounded and the upper portion of the lip 

 is expanded in a semi-circular curve. 



As usual in the genus two forms, probably sexual, are rep- 

 resented. The figured type is the more slender and is pre- 

 sumably the male. An example of the more inflated form 

 has the same number of whorls as the type, measures alt. 3.5, 

 diam. 3 mm. and has a somewhat wider umbilicus. 



