SubjainUies, Genera, and Subgenera — Recent and Fossil 89 



In Westerlund's list of the subgenera of Planorbis (1902, p. 120), the 

 type of Menetus is given as Planorbis boissyi P. and M., which is now 

 placed in the genus Afroplanorbis, the type of Menetus being Planorbis 

 opercidaris Gould. The comparison of Heterodiscus with Menetus would 

 indicate that the latter group was somewhat related to the African species 

 and the Latin description would fit, in a measure, some species, as adowensis 

 and suflanicus. The habitat of Planorbis libanicus is not so far removed 

 from the African region as to preclude the possibility that this species 

 might group with Afroplanorbis, hence the new name Syrioplanorbis 

 (Heterodiscus) would become a synonym of Afroplanorbis. Only an ex- 

 amination of the animal of libanicus would positively settle this question. 



Species Considered as Valid. Sijrioplanorbis libanicus (Westerlund) 

 is the only species attributable to this genus and, as indicated above, the 

 \'alidity of the generic concei:»t is not wholly certain. 



Genus BIOMPHALARIA Preston, 1910 

 Type by original designation Biomphalaria S)7iithi Preston 



1901. Plnnorhia J. E. S. Moore, To the Mountains of the Moon, p. 260. Monotype 

 Planana albertensis J. E. S. Moore (non Planarin Brown, 1827, or Miiller, 

 1776). 



1910. Biomphalarin Preston, Ann. Mag. N. H. (8), VI, p. 535, plate ix, figs. 26, 26a. 

 Tyjie Biomphalaria smithi Preston. As genus. 



1927. Planaria Pilsbry and Bequaert, Bull. Amer. Mus. N. H., LIII, p. 121. Monotype 

 Planaria albertensis J. E. S. Moore. 



1927. Biomphalaria Pilsbry and Bequ.\ert, op. cit., p. 115. Monotype Biomphalaria 

 smithi Preston. As .synonym of Planorbis Miiller. 



1931. Biomphalaria Thiele, Handbuch, Teil 2, p. 479. As section of genus Planorbis. 

 Tvpe wrongly given as Planorbis choanomphalus von Martens. 



1934. Biomphalaria Pilsbry, Proc. Phil. Acad. Nat. Sci., 86, p. 55. Type Biomphalaria 

 smithi Preston. 



1936. Biomphalaria Ha.a.s, Abh. Secken. Natur. Ge.sell., No. 431, p. 25. Type Biom- 

 phalaria smithi Preston. As genus. 



Shell (plate 81, fig. 4). Subdiscoidal, planulate with concave spire, last 

 whorl very large; umbilicus open, but shallow; aperture gaping; labrum 

 greatly receding below (Preston). The .shell is ultradextral. Of this species 

 Pilsbry says (1927, p. 120) 'The prominent character of this species is the 

 deviation towards the left of the last half-whorl.' Viewed as a dextral 

 species, the last part of the whorl drops below the periphery as in some 

 specimens of Gyraidus defiectus. 



Animal. The anatomy of the group is at present unknown. 



Geographical Distribution. Lake Albert Edward, Belgian Congo, 

 Africa. Only the type species is known. Planorbis ruppelli Dunker, Pla- 

 norbis choanomphalus Martens and Planorbis katangae Haas, included in 

 this genus by Haas (1936) appear to belong elsewhere. They do not have 

 the characteristics assigned to Biomphalaria. 



Species Considered as Valid. Biomphalaria smithi Preston is the sole 

 representative of the genus here recognized. 



Remarks. This genus is unknown anatomically and its true position in 

 planorbid nomenclature can not be definitely assigned until the animal has 

 been dissected. Pilsbry ( 1927, p. 120) suggests that it is a modification of 

 the Planorbis adoiuensis type and might be placed in the same section of 



