VIII. 

 GROUPS OF UNCERTAIN AFFINITIES 



Subfamily CHOANOMPHALINAE Germain, 1923 

 Characters those of the genus Choanomphalus Gerstfeldt 



Genus CHOANOMPHALUS Gerstfeldt, 1859 

 Type by original designation, Choanomphalus maacki Gerstfeldt 



1859. Choanomphalus Gerstfeldt, Ueber Land imd Siisswasser-mollusken Siberiens, 

 p. 527. Type Choanomphalus maacki Gerstfeldt. As genus 



1870. Choanomphalus Dall, Ann. N. Y. Lye. N. H., IX, pp. 353, 358. Type Choanom- 

 phalus maacki Gerstfeldt. As genus 



1875. Choanomphalus W. Dybowski, Die Gasteroi)oden Fauna Baikal-See. Mem. Acad. 

 Sci., St. Petersburg, Ser 7, XX, p. 52. Type Choanomphalus maacki Gerst. 

 As genus 



1879. Choanomphalus Crosse and Fischer, Jour, de Conch., XXVII, p. 160. Type 

 Choanomphalus maacki Gerst. As genus 



1883. Choanomphalus Fischer, Man. de Conch., p. 508. Type Choanomphalus maacki 



Gerst. As genus 



1884. Choanomphalus Tryon, S. and.S. Conch., IH, ji. 105. Type Choanomphahis 



maacki Gerst. As genus 



1885. Choanomphalus Westerlund, Fauna der palaarct. Region Binnenconchylien, V, 



p. 63. Type Choanomphalus maacki Gerst. As genus 



1886. Choanomphalus Clessin, Syst. Conch. Cab., XVII, p. 232. Type Choanompha- 



lus maacki Gerst. As genus 

 1909. Choanomphalus Lindholm, Mollusken, in Korotneff, Wissens. Ergebn. Zool. 



Exped. Baikal-See, IV, pp. 8, 93. Type Choanomphalus maacki Gerst. As 



genus 

 1923. Choanomphalus Germain, Rec. Ind. Mus., XXI, p. 190. Type Choanomphalus 



maacki Gerst. As genus 

 1925. Choanomphalus Dybowski and Grachmalichi, Kosmos, L, p. 877. As genus 

 1931. Choanomphalus Thiele, Handbuch, p. 482. Type Choanomphalus maacki Gerst. 



As genus 



Shell (plate 81, figs. 7, 8, 9) small, pseudodextral, turbinate, of few 

 whorls rather rapidly increasing in diameter, the spire depressed but not 

 flat, base widely umbilicated or with a small chink; aperture rounded. The 

 shell resembles some species of Valvata in form. 



Animal. Similar to Plonorbis in tentacles, jaw, and radula. Respiratory 

 and genital openings on the left side (see Dybowski and Grachmalichi, p. 

 870) . The eggs are laid in capsules with four to five eggs in each capsule. 

 The jaws are three in number with a large, half-moon-shaped superior jaw 

 and two small lateral jaws. 



The radula plate measures 1.6 mm. in length and 0.3 mm. in width, and 

 carries 175 rows of teeth. The formula of Choanomphalus maacki is (4)- 

 9-5-16-1-16-5-9- (4) (69 teeth in row) or sixteen lateral teeth, five inter- 

 mediate teeth, nine marginal teeth, and four outer marginal teeth without 

 distinct form. In Choanomphalus valvatoides the formula is (3) -10-5-10-1- 

 10-5-10- (3) (57 teeth in row). In Choanomphalus bicarinatus the formula 

 is 4-6-20-1-20-6-4 (61 teeth in row). Choanomphalus cryptomphalus has 

 the formula 5-6-20-1-20-6-5 (63 teeth in row). The smallest formula is 

 borne by Choanomphalus schrencki which is 4-7-1-7-4 (23 teeth in row), 



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