. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. POLYGYRA. 263 Fitr l'» Jaw of S. ventrosula. Jaw high, arcuate, onds scarcely altenuated, blunt, cutting edge witliout median projection; anterior surface with numerous stout, separated ribs, den- ticulating either nian^in. 1 have counted 8 ribs in P. ventrosula; 14 in pus- lula; 10 in aurlrulata; 12 in PoHteUiana; 12 in Carpenteriaua; 10 in pusfrcloides; 12 in avai'a : over 14 in cereolus; 10 in espi- ; 13 in uvuUfera; 10 in Texasiana Sixid triodonlaides: 12 in Troostiana; 11 \\\ leporina; 15 in Moor
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. POLYGYRA. 263 Fitr l'» Jaw of S. ventrosula. Jaw high, arcuate, onds scarcely altenuated, blunt, cutting edge witliout median projection; anterior surface with numerous stout, separated ribs, den- ticulating either nian^in. 1 have counted 8 ribs in P. ventrosula; 14 in pus- lula; 10 in aurlrulata; 12 in PoHteUiana; 12 in Carpenteriaua; 10 in pusfrcloides; 12 in avai'a : over 14 in cereolus; 10 in espi- ; 13 in uvuUfera; 10 in Texasiana Sixid triodonlaides: 12 in Troostiana; 11 \\\ leporina; 15 in Mooreana; 20 in fasligdns : 7 in septemvolca; 10 in Febifjeri; in Hazardi and aurlformts they are also numerous. I have had no opportunity of examin- ing the jaw in the other species found within our limits Hindsi, tholus, hippocrepis, oppilata, DorfeuilLiana, Ariadnce, By the character of its jaw, Pobjgyra can be compared only lo Triodopsis and Mesodon among the other North American subgenera of Helix. No foreign species has yet been examined. Fig. 158 shows the general arrangement of the teeth upon the lingual mem- brane, the characters of the individual teeth being better shown in my PI. VI. Fig. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harvard University. Museum of Comparative Zoology. Cambridge, Mass. : The Museum
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