Pars92 Laevapex — Gundlachia — Amphigyra — Neoplanorbis — 1708 
Genus Laevapex Walker 1903.15) 
Genotyp: Laevapex fuscus (C. B, Adams). 
Subgenus Ferrissia Walker 1903.) 
Genotyp: Laevapex (Ferrissia) rivularis (Say). 
Syn. ?Haldemania Clessin, 18827?) (non Tryon, 1862!). 
Laevapex (Ferrissia) undulatus (Meek). 
*1870 Ancylus undulatus, Meek, (70a) Proceed. Acad. Nat. Sci. Phila- 
delphia 1870, p. 57. 
1877  Ancylus undulatus, Meek, (77a) United States Geological Explo- 
rations of the Fortieth Parallel (Clarence King) Paleontology 
IV, pt. I, p. 186, tab. XVII, fig. 12a—b. 
1877 Ancylus undulatus, White, (77c) Bull, U. S. Geol. and Geogr. 
Survey of the Territories III, p. 614. 
1881 Ancylus undulatus, S. A. Miller, (79a) The Journ. of the Cin- 
cinnati Soc. of Nat. Hist. IV, (1881), p. 39. 
1882 Ancylus undulatus, White, (82c) Proceed. U. S. National Mu- 
seum V, p. 100, tab. V, fig. 10—11. 
1883 Ancylus undulatus, White, (83a) Report U. S. Geol, Survey III, 
. (1882/83), p. 451, tab. XXXII, fig. 10. 
1885  Ancylus undulatus, Marcou, (85a) Proceed. U. S. National Mu- 
seum VIII, p. 339. 
1913  Laevapex (Ferrissia) undulatus, Hannibal, (12a) Proceed. Mala- 
cological Soc. London X, p. 151. 
Vorkommen: ?Eocün: Truckee Lake Beds: Kawsoh 
Mountains (Nevada), Fossil Hill (Hotspring Mountains 
(Idaho). 
Genus Gundlachia Pfeiffer 1849.7?!) 
Genotyp: Gundlachia ancyliformis (Pfeiffer). 
Syn. Poeya Bourguignat, 1862.7) 
Gundlachia aucylilormis Pfeifter. 
(1850 Gundlachia ancyliformis, Pfeiffer. Zeitschr. f. Malakozool. VI. 
(1849), p. 98.) 
1874 QGundlachia ancyliformis, Guppy, (74a) The Geological Magazine. 
N. S; Dec. II, vol Ll, p. 437. 
Vorkommen: O. Pliocàn: Trinidad. 
Genus Amphigyra Pilsbry 1906,7??) 
Genotyp: Amphigyra alabamensis Pilsbry. 
Subgenus Neoplanorbis Pilsbry 1906.77!) 
Genotyp: Amphigyra (Neoplanorbis) tantillus Pilsbry. 

78) The Nautilus XVII, p. 15. 
719) The Nautilus XVII, p. 15, 
79) Martini- Chemnitz, Syst. Conchylien-Cabinet. Ancylinen. p. 
1&, 15, 
771) Zeitschr. f. Malakozoologie 1849, p. 97. 
7:2) Les spiciléges malacologiques. p. 85. 
733) The Nautilus XX, p. 49. 
7^' The Nautilus XX, p. 50. 

