Occasional Papers of the Museum of Zoology 27) 
AMNICOLIDAE 
Amnicola guatemalensis 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, vu, d). These speci- 
mens are narrowly imperforate to almost rimate. 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 coronatus (Pfeiffer)—A_ single specimen 
from the Laguna de Chacalapa, a large savannah pond (H, vi). 
AMPULLARIIDAE 
Ampullaria flagellata Say (1827). 
A. malleata Jonas (1844). 
A. malleata, var. exculpta 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. malleata Jonas. A. flagellata 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—1. 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 Heightaperture Diameter aperture 
50 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.) 
