R24 THE CHICAGO ACADEMY OF SCIENCES. 
GENITALIA: In almost all respects like those of cubensis and 
techella. Measurements are as follows: 
Prost. Penis-sac 
Penis. Penis-sac. Vas. def. duct. Ree, sem. Penis ret. ret. Shell. 
1.25 2.00 8.00 2.00 2.00 1.10 1.50 7.00 
The penis-sac retractor is much enlarged as it enters the penis-sac, 
the whole muscle forming a broad band of tissue; the penis retractor 
is long and narrow, and enters the columellar muscle at the same point 
as the penis-sac retractor. The receptaculum seminis is ovate-quad- 
rangular in outline. 
Rance: Colorado. A species of the Coloradoan region. 
RECORDS. 
CoLtorapo: West of Fort Collins, Larimer Co. (Henderson). 
Ecotocy: Inhabits lagoons and intermittent bodies of water. Mr. 
Henderson writes of the habitat as follows: “I am informed that there 
had been no water in the lagoon for many months, probably not since 
jast summer or autumn. The ground was cracked to a depth of 
several inches and the mollusks were found down in the cracks and 
in the mud. Therefore, it seems to be another species capable of 
aestivating.” 
Remarks: This species was at first thought to be Galba sono- 
meensis Hemphill, but a comparison with that species shows that the 
present species differs not only from sonomensis but from all related 
species in the form of the spire and aperture. The first two whorls 
cf the spire are coiled in the same plane, producing a sharply truncated 
appearance. The outline of the shell is also more ovate than in sono- 
mensis and the aperture is not expanded. The inner lip is also rolled 
over to a greater extent than in the Sonoma species, and approaches 
closely to some individuals of bulimoides. The only Lymnezeid likely 
to be confounded with hendersoni is sonomensis, which differs in the 
form of the spire and inner lip. 
I take great pleasure in dedicating this interesting species to Judge 
Junius Henderson, of the University of Colorado. 
Galba perpolita (Dall). Plate XXVIII, figure 19. 
Lymnea (Stagnicola) perpolita Dati, Alaska Moll., p. 78, pl. 2, figs. 6, 8, 
1905. 
Lymnea perpolita Pitspry, Nautilus, XTX, p. 95, 1905. 
“SHeLLt: Small, translucent, dark amber color, with a darker line 
at resting stages; smooth, except for fine lines of growth, brilliantly 
polished; whorls four, tumid, rapidly increasing, separated by a pro- 
nounced suture ; spire short, rather obtuse; aperture ovate, longer than 
the spire, with a very thin wash of callus on the spire, the pillar lip 
