32 University of Michigan 
Part II. OPprERCULATES 
HELICINIDAE! 
Oligyra (Succincta) flavida strebeli (Pfeiffer). 
H, flavida Menke (1829). The usually larger, more southern, 
banded form. 
H. trossula Morelet (1849). A synonym of the preceding. 
H. brevilabris Pfeiffer (1857). From description, a still larger 
form. 
Hi. strebeli Pfeiffer (1861). Usually smaller, thinner and more 
depressed, with 5 to 544 whorls; used here as subspecies. 
About 800 adults; from leaves of trees, shrubs and vines 
(H, I, b), and on the ground (H, I, a) in the lowland forest; 
dead shells from the burnt-over area (H, II, a) ; from leaves 
of shrubs, cacti, etc., in the savannah forests (H, III, m) ; and 
from shrubs and elephant-ears along Arroyo Hueyapam (H, 
JEL, 10). 
None of the specimens are banded, but the ground-color 
varies from vitreous white and milky white, through horn- 
colored and greenish horn-colored, to yellow and dark amber- 
brown. The last two color-forms are especially striking. The 
lip is always milky white. Extremes measure: 
Altitude Greatest diameter Heightaperture Diameter aperture 
6.1 mm. 93 (5.7 mm.) 48 (2.9 mm.) 52 (3.2 mim.) 
4.5 mm. 102 (4.6 mm.) 53 (2.4 mm.) 58 (2.6 mm.) 2 
The spiral striations in these specimens are very variable; 
they may be quite well developed or almost completely absent. 
1The radulae of the four species included here have been exam- 
ined and are figured in another paper, “Notes on the Radula of the 
Helicinidae,” which will appear in the Proc. Acad. Nat. Sci. of Phil- 
adelphia. As the synonymy of the North American mainland species 
is also treated in that paper, it is omitted here, except where it is 
actually discussed. 
2 Throughout this paper, the altitude is expressed in millimeters, 
but the other dimensions are expressed as indices. The index of each 
dimension is taken as that dimension divided by the altitude. ‘The 
index is followed by the actual dimension in millimeters. 
