. Bulletin - United States National Museum. Science. 254 A MANUAL OF AMERICAN LAND SHELLS. Fig. 267. ting points even in the same lingual membrane, but as a general thing it may be said that the marginal teeth are but a modification of the form of the laterals. They decrease in size greatly at the outer edge of the lingual membrane. It must be borne in mind that the cutting points vary in develop- ment on difi'erent portions of any one lingual membrane. I have in each case chosen for drawing such individual teeth as appear best to illustrate the general character of the dentition (in Terr. Mol
. Bulletin - United States National Museum. Science. 254 A MANUAL OF AMERICAN LAND SHELLS. Fig. 267. ting points even in the same lingual membrane, but as a general thing it may be said that the marginal teeth are but a modification of the form of the laterals. They decrease in size greatly at the outer edge of the lingual membrane. It must be borne in mind that the cutting points vary in develop- ment on difi'erent portions of any one lingual membrane. I have in each case chosen for drawing such individual teeth as appear best to illustrate the general character of the dentition (in Terr. Moll., V). It will be seen that Patula differs from all the genera of Limacidw and Agnatha by the presence of quadrate, not aculeate, marginal teeth, a character shared by all the succeeding genera. There does not appear any very essential character in the dentition by which to distinguish it from manj' of the other American genera of disintegrated Helix, as will be seen below. It will be noticed that one species, asteriscus, has mar- ginal teeth like those of Pvpa and Vertigo. Patula solitaria, Say. Shell broadly umbilicated, globosely depressed, coarse, solid, diaph- anous, obliquely arid crowdedly wrinkled, from white to dark-reddish horn-color, with from two to three brownish revolving bands : whorls 6, con- vex ; suture deep ; aperture roundedly lunate, pearly white and banded within; peristome sim- ple, acute, its ends joined by a thin, transparent callus, that of the columella dilated, subreflected. Greater diameter 25, lesser 22'"'"; height, 15'""'. Helix solitaria, Say, Journ. Phila. Acad., ii, 157 (1821); Binney's ed., 19.—De Kay, N. Y. Moll., 43, pi. iii, fig. 41 (1843).—Binney, Bost. Journ. Nat, Hist., iii, 426, pi. xxii (1840); Terr. Moll., ii, 20«, pi. xxiv.—Chemnitz, ed. 2, i, 180, pi. xxiv, figs. 5, 6.—Pfeiffer, Symbolae, ii, 39; Mon. Hel. Viv., i, 102.— Reeve, Con. Icon., 662 (1852).—W. G. Binney, Terr. Moll., iv, 96.—Leidy, T. M
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