172 The MoUuscau Family Plauorbidae 



Linnean, furthermore, he applied the name to a minute species about an 

 eighth of an inch in diameter. In 1847, Gray (P.Z.S., p. 508) used the name 

 Coretus, as of Adanson, but definitely cited the Helix cornea of Linnaeus 

 as the type. Later authors (Wenz, 1923, Haas, 1929) use Coretus Gray, 

 1847, with the type Helix cornea. 



In 1806, Dumeril (Zool. Analyt., p. 164) coined the name Planorbarius 

 for a group of mollusks, without an operculum, inhabiting fresh water. 

 Except for the name, which suggests Planorbis, the group might pass for 

 anything among fresh-water pulmonates and the name is absolutely use- 

 less for purposes of nomenclature. In a German edition of Dumeril's work, 

 however, Froriep used this name and supplied a type, the Helix cornea 

 of Linnaeus which, according to Opinion 46 of the International Code, 

 becomes the monogenotype of the genus Planorbarius of Froriep. This 

 antedates INIontfort's use of corneus as a genotype by four years. 



Froriep says of Planorbarius in his German translation (p. 165) : 



Die Scheibenschnecken {Planorbarius) iinterscheiden sich (die Schaele ubemick- 

 sichtiget) \on den vorigen niir durch den mangelnden Schliessdeckel. Es sind dies 

 Flussschnecken. Z.B., Helix cornea. 



The case is much better than that of Coretus Gray and there appears to be 

 no reason why Planorbarius, as published by Froriep, should not be used 

 for the large European snail jireviously known as Planorbis corneus. The 

 rarity of Froriep's translation in libraries has doubtless been the cause of 

 its being omitted in most })rcvious discussions of planorbid nomenclature. 



Subfamily PLANORBULINAE Pilsbry, 1934 



Prostate diverticula compound but not fan-like in section, there being a 

 main division from which branch, on one side, several (four to six) smaller 

 diverticula. The ovotestis diverticula are placed in pairs. There is a pcnial 

 gland but no external duct, which is always placed inside of the preputium. 

 The jaws are as in Helisomatinae. 



Type genus Planorbula Haldeman. 



The few groups belonging in this subfamily are noted below: 



With short, tube-like duct: Planorbula, Proynenelus. 



Without distinct duct but with open channel: Menetus, Micromcnctus. 



The fossil group Planobifex Pilsbry doubtless belongs in this subfamily. 



Genus PLANORBULA Haldeman. 1840 

 Type by original designation Plajwrbis armigerus Say 



1840. Di.-<c}(s Haldeman, Mon. Limn. Part I, p. 4 of cover, July, 1840. Non Fitzinger, 

 1833, a land genus. Type Planorbis armigerus Say. As subgenus 



1840. Planorbula Haldeman, op. cit., Suppl. to Part I, p. 2 (Oct. 1840). New name for 

 Discus Haldeman, preoccupied 



1842. Planorbula H.'VLDEman, Mon. Limn., Part IV, Physidae, p. 14. Monotype Pla- 

 norbis arynigerus Say. As subgenus 



1847. Dentatus Gray, Proc. Zool. Soc. London, p. 181, non Beck, 1837. Type Planor- 

 bis armatus Gray, supposed to be the same as Playwrbis armigerus Say. As 

 subgenus of Coretus 



1855. Plariorbula H. and A. Adams, Genera of Rec. Moll., II, p. 265. Type Planorbis 

 armigerus Say. As subgenus 



1865. Planorbula Binney, L. and FW. Sh. N. A., II, p. 136. No type cited, but 

 Planorbis armigerus Say by assumption. As subgenus of Segmentina 



