. Bulletin - United States National Museum. Science. 414 A MANUAL OF AMERICAN LAND SHELLS. delicate ribs upon its snrfiice. There are over 50 ribs on tlie jaw of the only one of our species I have examined, ilf. Gossei. I give a copy of Mr. Bland's figure of the jaw of J7. signatus, which is similar. The lingual membrane of Macroceramns was supposed to be the same as in CylindreUa, described , as that of M. signatus was so found by Mr. Bland (Ann. Lye. Nat. Hist. N. Y., VIII, 162) and Crosse and Fischer (Journ. de Conch., 1870, Plate III, Figs. 14-16). It was, therefore, with surprise th
. Bulletin - United States National Museum. Science. 414 A MANUAL OF AMERICAN LAND SHELLS. delicate ribs upon its snrfiice. There are over 50 ribs on tlie jaw of the only one of our species I have examined, ilf. Gossei. I give a copy of Mr. Bland's figure of the jaw of J7. signatus, which is similar. The lingual membrane of Macroceramns was supposed to be the same as in CylindreUa, described , as that of M. signatus was so found by Mr. Bland (Ann. Lye. Nat. Hist. N. Y., VIII, 162) and Crosse and Fischer (Journ. de Conch., 1870, Plate III, Figs. 14-16). It was, therefore, with surprise that I found an entirely different type of dentition in M. Gossei. I can in this place only note the difference, and leave to future study the question of its bearing on the generic position of the species. M. Gossei (Plate X, Fig. Q, of Terr. Moll.; see )hasa membrane very long and narrow; teeth about 40-1-40, in scarcely oblique transverse rows, decidedly not en chevron. Centrals with a long, narrow base of at- tachment, with somewhat expanded lower lateral angles, its upper margin squarely reflected. The Lingual dentition of M. Gossei. reflected portion is very small, and bears three short, blunt cusps, the median the largest, all three with distinct cutting points. The base of attachment of the laterals is long and narrow, its outer lower angle irregularly cut away; the upper margin broadly and obliquely reflecte<l, the reflected portion thrown off' ob- liquely towards the margin of the lingual membrane, very short, and bearing two stout, bhmt, short cnsps, the inner the larger, also thrown obliquel}' towards the outer margin of the membrane; both of the cusps bear distinct cutting points, the outer one small, the inner one narrow, blunt, almost as long as the base of attachment. There are no distinct marginals, the laterals decreasing in size as they pass off laterally, those at the edge of the membrane having one large inner cutting point and several oute
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