Subfaf/iilies, Genera, and Subgenera — Recent and Fossil 65 



two on the iipjxT part of the aperture. The whole edge of the aperture is 

 thickened. 



Geological Distribution. Lower PHocene. Fonyod, Kenese, and Nagy- 

 vazsong. Hungary. 



Remarks. This group is noteworthy for the presence in the aperture of 

 three folds or plicae, whence the generic name Odontogyrorbis. In general 

 form the shell is related to Anisus vortex (Linn.), but is very much smaller. 

 Halavats original specimens (plate 76, fig. 1) were broken and did not 

 have the folds in the aperture. Lorenthey obtained specimens with the lip 

 entire (plate 76, fig. 2). Wenz (1923, p. 1538) made Odontogyrorbis a 

 subgenus of Paraspira {= Anisus). While the shell does resemble the type 

 of Paraspira [Planorbis leucosfonms ^Millet) no member of the genus 

 Anisus has as yet been recorded from the recent fauna with a dentate 

 aperture. For the present Odontogyrorbis should be treated as an extinct 

 genus related to Anisus. 



Species Considered as Valid. Odontogyrorbis krauibcrgeri (Halavats) 

 is the only si:)ecies here ascribed to the genus Odontogyrorbis. 



It is of interest to note that the Pliocene planorbid fauna of the Lake 

 Balaton region consist of sixteen species, all but one of which are extinct, 

 the Pleistocene fauna contains fifteen species and races all of which belong 

 to the recent fauna. Some of the supposed extinct species are closely related 

 to their recent allies and might be considered geologic variations of the 

 recent forms, in fact, ancestral species. 



Genus GYRAULUS (Agassiz :MS) Charpentier. 1837 



Type Planorbifi albii.s Miiller {^Planorbis hispidus Drap.) 

 Designated by Dall in 1870. The first species originally included. 



1827. Planaria (part) Brown, Illust. Conch. Britain, ed. 1, exphm. plate LI, figs. 48, 49. 



Xon Miiller 1886 and Golze 1782 (Vermes). 

 1837. Gyraulus (Agassiz MS) Charpentier. Xeue Denkschr. Allij. Schweiz. Gesell. 



I, no. 2, p. 21. 



1840. Gyraidus H.artmaxn, Syst. Uebers. Euroji. Gattun. (Tableau). 



1841. Trochlea Haldeman, Amer. Jour. Sci., XLII, p. 216. Xew name for Planaria. 



Brown. 

 1844. Gyraulus Hartmaxx, FAxi unil Siissw. Gaster. der Schweiz. V. p. 89. 

 1850. Nnutilina Stein, Leb. Schneck. und Muschl. Berlins, p. 80. Tyjie fixed by 



Clessin (1886) Planorbis albus Miiller. As synonym of Gyraulu.^. 

 1855. Gyraulus Moquin-Tandon, Hist. X"at. Moll. France, II, p. 438. X'o type cited. 



As genus. 

 1855. Giraulus Moquin-Tandon, op. cit., p. 423. Tyjiographical error for Gyraulus. 

 1857. Gyraulus Gray, Turtons Manual. 2nd Ed., p. 234. In sj'iionj-my. 

 1857. Gyrulus Gr.\y, op. cit., p. 234. Error for Gyraulus. 



1865. Gyraidus W. G. Binney, L. & F-W Sh. X. A., II, p. 128. Xo type cited. As .sub- 

 genus of Planorbis. 

 1870. Gyraulu.'i D.\ll, Ann. X. Y. Lye. X"^at. Hist., IX, p. 351. Type Planorbis albus 



Miiller. As subgenus of Planorbis. 

 1883. Gyraulus Fischer, Man. Conch., p. 507. Type Planorbis albus Miiller. As section 



of Planorbis. 

 1883. Caillaudia Bourciuign.at, Ann. Soc. Xat. Zool., (6), XV, p. 99. Monotype Cail- 



laudia angulata Bo\\rg. = Planorbis costulatus Krauss. (vide Pilsbrj' and 



Bequaert, 1927, p. 124). 



