. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 314 TERRESTRIAL AIR-BREATHING MOLLUSKS. Its peculiar surface, resembling a scaly coat of mail, when closely examined, is highly characteristic. Jaw long, broad, slightly arched, ends blunt, but little attenuated; with 11 broad, stout, crowded ribs, visible on both anterior and posterior surface, and crenulating either margin. T. loricata (PI. VII. Fig. J) has over 20—1—20 teeth on its lingual mem- brane ; 8 perfect laterals. Genitalia not observed. MESODON, Raf. Animal as in Patula (q. v.) ; mantle subcentral
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology; Zoology. 314 TERRESTRIAL AIR-BREATHING MOLLUSKS. Its peculiar surface, resembling a scaly coat of mail, when closely examined, is highly characteristic. Jaw long, broad, slightly arched, ends blunt, but little attenuated; with 11 broad, stout, crowded ribs, visible on both anterior and posterior surface, and crenulating either margin. T. loricata (PI. VII. Fig. J) has over 20—1—20 teeth on its lingual mem- brane ; 8 perfect laterals. Genitalia not observed. MESODON, Raf. Animal as in Patula (q. v.) ; mantle subcentral. Shell umbilicated, or with the umbilicus closed, subglobose or orbicularly de- pressed, thin, delicately striate, sometimes decussatedly sculptured; whorls 5 - 6, regular; aperture rotundly lunar, sometimes narrowed by a small denticle on the parietal wall; peristome thickened Avith white, expansively reflexed, its basal marjiin sometimes unidentate. A genus strictly North American, widely distributed over the Eastern Prov- ince, scarcely represented in the Central or Pacific Provinces. It has come down from Post-pleiocene days. Jaw stout, high, arcuate, wide, ends but little attenuated, blunt; no median projection to the cutting margin; anterior surface Avlth numerous, separated, decided ribs, denticulating either margin. I have counted 13 in M major ; 10 in albolabris; 10 in multilineata; 11 in Pennsyloanica; V2 in Mitchelliana; 12 in elevata; 13 in Clarki; 13 in exoleta; 18 in Wetherhyi; 14 in dentifera; 7 in Roe- meri; 13 in thyroides; 10 in clausa; Sin Cohonbiana ;^ 7 in devia; 10 in pro- funda; 15 in Sayii; 10 in Mobilicma ; over 10 in Downieana; 10 in Christyi and divesta. ^'"" "^'^" I have had no opportunity of examining M. Wheatleyi, and Jejuna. Nothing has been published regarding the jaw and lingual dentition of the subgenus from species foreijjrn to North America, as it is ex- Jaw of M. Sayii (Morse). ^ '=' clusively confined to this countr
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Keywords: ., bookauthorha, bookcentury1800, bookdecade1860, booksubjectzoology
