Occasional Papers of the Muse it in of Zoology 37 



AMNICOLIDAE 



Amnicola guatcmalcnsis Crosse and Fischer. — Very numer- 

 ous, under bits of lava and pumice, on the north shore of 

 Lake Catemaco, and also on the opposite side of the lake, in 

 shallow water near a sulphur spring (H, vii, d). These speci- 

 mens are narrowly imperforate to almost ririiate. The original 

 description does not mention the microscopic, raised, spiral 

 lines ; these are not very evident on the adults, but are very 

 noticeable in the young specimens. The operculum is thin, 

 corneous, and from dark brown to almost black in color. It 

 is three-quarters spiral, with evident, raised ridges parallel to 

 the growth-lines. The radula is shown in figure 5. In certain 

 lights, the outer tooth may be seen to be striated longitudinally 

 for almost its entire length. 



Potamopyrgus coronatits (Pfeiffer). — A single specimen 

 from the Laguna de Chacalapa, a large savannah pond (H, vi). 



AMPULI^ARIIDAE 



AmpuUaria Hagellata Say (1827). 

 A. malleata Jonas (1844). 

 A. malleata, var. cxculpfa C. and F. (1890). 

 A. malleata, var. arata C. and F. (1890). 



Twenty specimens. Some of the shells from the larger for- 

 est pools near La Laja (H, v, a) are quite typical of what is 

 often cited as A. nmlleata Jonas. A. Hagellata represents a 

 shell with a slightly more flaring lip than is general, but is not, 

 I believe, even subspecificly distinct. Two of the shells are 

 close to the figures of arata — i. e., they practically lack the 

 malleation. The term exculpta appears to include the more 

 malleated forms and does not appear even racially distinct. 

 All of the shells in this lot are rather small ; the largest 

 measure : 



Altitude Greatest diameter Height aperture Diameter aperture 



SO mm. 87 (43.5 mm.) 71 (35.7 mm.) 52 (25.8 mm.) 



47.5 mm. 88 (41.7 mm.) 76 (36.1 mm.) 57 (26.7 mm.) 



