48 The Molluscan Family Planorhidae 



Key to Genera of Planorbulinae* 



la. Penial gland sausage-shaped with round, closed duct 2 



b. Penial gland flattened, ovate, with open, channel-like duct 3 



2a. Penial duct very short leading from gland direct to muscular collar or 



diaphragm Menet us s.s. (see p. 183) . 



b. Penial duct long, extending up the side of the preputium to the muscular 



collar or diaphragm (Subgenus) Micromenetus (see p. 187). 



3a. Penial gland connected with muscular collar by an open duct as long as the 

 gland, lying above a single diagonal projection of the left pilaster; seminal 

 vesicle composed of many diverticula forming a mulberry appearance on 



the surface Flanorbuln s.s. (.sec \\. 173). 



b. Penial gland connected with muscular collar by an open slit in the muscular 

 wall of the preputium, the two pilasters sending branches from both sides 

 to this slit; seminal vesicle consisting of many short diverticula stretched 

 along a large part of the ovisperm duct Frotnenetus (see p. 178). 



SYSTEMATIC LIST OF GENERA AND SUBGENERA 

 RECOGNIZED IN THIS WORK 



In the following list the genera and subgenera are arranged in the sequence 

 which appears most in accord with their structural features. Several groups 

 are unknown anatomically and these are marked by an asterisk. They are 

 placed in the subfamilies and near the genera with which they appear to 

 be affiliated. The fossil species, it is obvious, can never be known anatomi- 

 cally and these are placed near those genera which they most nearly re- 

 semble. The fossil groups are marked by a dagger. Two groups of uncertain 

 affinities, one recent and one fossil, are placed at the end of the family 

 sequence. The type species is indicated following the name of each genus 

 or subgenus. 



Family PLANORBIDAE H. and A. Adams, 1855 

 Subfamily Planorbinae Pilsln-y, 1934 



Genus Planorbis Geoffrov, 1767 Helix planorbis Linn. 



Genus Anisus Studer, 1820 (Gray, 1847) 



Subgenus Anisus SS Helix spirorbis Linn. 



Subgenus Costorbis Lindholm,t 1926 Planorbis strauchianus Clessin 



Subgenus Bathyomphalus (Ag.) Charp., 1837. .Helix contorta Linn. 



Genus Odontogyrorbis L6renthey,t 1906 Planorbis krambergeri Halavdts 



Genus Gyraulus (Ag.) Charp., 1837 



Subgenus Gyraulus SS Planorbis albiis Miiller 



Subgenus Torquis Dall, 1905 Planorbis parvus Say 



Genus Armiger Hartmann, 1840 Nautilus crista Linn. 



Genus Taphius H. and A. Adams, 1855 Planorbis andecolus Orb. 



Genus Tropicorbis Pilsbry and Brown, 1914 



Subgenus Tropicorbis" SS P. liebmanni T>nn\s.Qr = orbiculus 



Morelet 



Subgenus Obstructio Haas, 1939 Planorbis janeirensis Clessin 



Subgenus Lateorbis F. C. Baker (New) Planorbis pallidus C. B. Adams 



Genus Afroplanorbis Thiele, 1931 Planorbis sudanicus Martens 



Genus Syrioplanorbis F. C. Baker, f new name for 



Heterodfscus West., preoccupied Planorbis libanicus West. 



Genus Biomphalaria Preston, f 1910 Biomphalaria smithi Preston 



Genus Australorbis Pilsbry, 1934 Planorbis glabratus Say 



Genus Anisopsis Sandberger,t 1875 Planorbis calculus Sandberger 



*One subgenus is included in this key. 



tThe anatomy is not known for any member of this group. 



JA group represented by fossils only. 



