. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 376 TERRESTRIAL AIR-BREATHING MOLLUSKS. Fig. E. Tryoni. horn-color; whorls 5 to 6, scarcely convex, the last globose, descending towards the aperture, inflated below; aperture oblique, subcircular, small, witbin dark above, lighter below ; peristome thickened, dirty white, its terminations somewhat converging, joined by a light cal- lus, right margin slightly expanded, not reflected, that of the columella dilated, scarcely reflected, appressed, ob- tusely subdentate. Greater diameter 24, lesser 20 mill.; height,
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 376 TERRESTRIAL AIR-BREATHING MOLLUSKS. Fig. E. Tryoni. horn-color; whorls 5 to 6, scarcely convex, the last globose, descending towards the aperture, inflated below; aperture oblique, subcircular, small, witbin dark above, lighter below ; peristome thickened, dirty white, its terminations somewhat converging, joined by a light cal- lus, right margin slightly expanded, not reflected, that of the columella dilated, scarcely reflected, appressed, ob- tusely subdentate. Greater diameter 24, lesser 20 mill.; height, 14 mill. Helix Tryoni, Newcomb, Proc. Cal. Acad. Nat. Sci., III. 116 (1864). — W. G. Binney, Am. Journ. Conch., I. 47, PI. VI. Figs. 1-10 (1865) ; L. & Sh., I. 178 (1869). Polymita Tryoni, Tryon, Am. Journ. Couch., II. 319 (1866). California Region, on Santa Barbara Island and San Nicholas Island, Califor- nia, both recent and fossil, the latter form very large and thick; not on San Clemente. The species varies in the greater or lesser development of the spire, and in coloring. The form figured differs from that described in having the under as well as upper surface mottled, not a dead white; an albino form is also found; also a fourth variety of a uniform cream-color, showing, however, slight traces of the revolving band. The animal is black. It has a thick, white, parchment-like epiphragm. Jaw arcuate, of uniform width throughout, ends blunt; anterior surface with stout ribs, denticulating either margin. Figures of the jaws of nine mature in- dividuals are given, showing that the number and arrangement of the ribs is not constant; a fact noticed in other species. 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. : Th
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