55 {54) Test is relatively small with few whorls of equal size; wall is 

 translucent and glossy. Diameter 0.20-0.22 mm. a, Side view; 

 b, edge view Cornuspira planorbis 



X150 



55 (54) Test is relatively large with many overlapping whorls; wall is opaque. 



Diameter 1 .00 mm or larger, a, Side view; b, edge view Cornuspira involvens 



56 (54) Two chambers only are visible from the exterior; test is 

 subglobular; aperture is large, rounded, with a low bifid tooth. 

 Length 0.40-0.60 mm. a, Front view; b, side view; c, top 

 view Pyrgo subsphaerica 



X60 



56 (54) More than two chambers are visible from the exterior 57 



57 (56) Four chambers are visible from one side and three from the other (quinqueloculine) 

 57 (56) Three chambers are visible from one side and two from the other (triloculine) 



.58 

 .64 



58 (57) Aperture lacks a tooth; test is flattened, nearly circular in 

 outline, rounded on the periphery. Length 0.30-0.55 mm. 

 a, b. Opposite sides; c, top view Pateoris hauerinoides 



X60 



58 (57) Aperture has a tooth 59 



20 



