28 GASTROCOPTA, NORTH AMERICA, WEST INDIES. 



a 1 . With no distinct palatal callous. 



b. Ovate-conic, with 4 to 5 teeth ; 1.2 x 1 mm. 



6r. carnegiei, no. 6. 

 & 1 . Cylindric, with 5 teeth; 1.6 to 1.9 mm. long. 



G. pilsbryana, no. 7. 



4. GASTROCOPTA PENTODON (Say). PI. 3, figs. 2, 3, 5 to 8; 



pi. 4; pi. 5, figs. 28 to 41. 



The shell is rimate, oblong-conic with obtuse summit, clear 

 corneous or whitish, smooth. Whorls 5, convex, the last with 

 a rounded ridge or crest (low or well developed) close behind 

 the lip, and flattened near the base behind the ridge. Aper- 

 ture short, truncate-oval. Teeth typically five, the angulo- 

 parietal lamella almost simple and straight, columellar lamella 

 thin, horizontal; the palatal plicae stand upon a low callous 

 ridge, the lower plica compressed and entering a little more 

 deeply than the smaller, tuberculiform upper one. Accessory 

 denticles are usually developed in the subcolumellar, basal 

 and interpalatal positions. The peristome is thin, narrowly 

 expanded, with a thin, straight, parietal callous between the 

 widely separated ends. 



Length 1.8, diam. 1.1 mm. 



Length 1.7, diam. 1 mm. 



Length 1.5, diam. 0.8 mm. 



Eastern United States and Canada: Prince Edward and 

 Magdalen Islands to Alberta, south to central Florida and 

 Texas; New Mexico; west in Arizona to the Santa Cruz 

 River. Eastern Mexico and Guatemala. Type locality, Penn- 

 sylvania. 



Vertigo pentodon SAY, Journal Acad. Nat. Sci. Phila., ii, 

 1821, p. 376. Pupa pentodon (in part) BINNEY, Terrestrial 

 Mollusks, v, 1878, p. 200. PFEIFFER, Monogr. Hel. Viv., ii, 

 359; iii, 557; iv, 684; vi, 330; viii, tt)2.Bifidaria pentodon 

 Say, PILSBRY and VANATTA, Nautilus, xix, p. 121, pi. 6, 7, 

 figs. 1 to 41. WALKER, Occ. Pap. Mus. Zool. Univ. Mich., 

 No. 15, 1915, pp. 9-11. Pupa curvidens GOULD, Report on 

 the Invertebrata of Massachusetts, 1841, p. 189, fig. 120 

 Pupa cincinnatiensis JUDGE, The Quarterly Journal of Con- 



