88 The MoUuscan Family Planorhidae 



The African group would appear properly to take the name Afropla- 

 norbis proposed by Thiele, preferably as a genus closely related to 

 Tropicorbis. It has no relationship with Planorbula Haldeman which is 

 purely an American genus belonging to a different subfamily. The close 

 relationship between Tropicorbis of Central and South America and the 

 African species here referred to Ajroplanorbis is, as pointed out by Pilsbry 

 (1934, p. 55), an interesting parallel in zoogeography. A similar relation- 

 ship is found in the Ancylidae and in some groups of land shells. 



In a recent work (1939, p. 483) Connolly uses the generic name 

 Biomphalaria Preston for all of the African species once referred to Pla- 

 norbula. However, the anatomy of the type of this genus, smithi Preston, 

 is unknown and until that species has been examined anatomically it 

 would seem unwise to use this name so inclusively. Should the anatomy 

 jirove to be like that of the two species here referred to the genus Ajro- 

 planorbis, Planorbis adowensis and P. pfeifferi, it would then take prece- 

 dence over Ajroplanorbis which would become a synonym of Biomphalaria. 

 Tropicorbis appears to be generically distinct from the African species and 

 can not be included in either Ajroplanorbis or Biomphalaria, as suggested 

 by Connolly (p. 484j. 



Genus SYRIOPLAXORBIS F. C. Baker 



New name for HETF]RODISCUS Westerlund, preoccupied. Type 

 Planorbis libanicus Westerlund, originally designated for HETERODISCUS 



1902. Hetcrodiscus Westerluxd, Rad. Jugoslav. Akad., 151, p. 120. Tj'pe Planorbis 

 libanicus Westerlund. As subgenus of Planorbis. Non Heterodiscus Sharp, 

 Insecta, 1886. 

 1905. Heterodiscus Dall, Alaska Moll., p. 83. Type Planorbis libanicus Westerlund, 



As section of Planorbis. 

 1931. Heterodiscus Thiele, Handbuch, Teil 2, p. 479. Type Planorbis libanicus Wester- 

 lund. As section of Planorbis. 

 'Shell n: t. media (d. 14 mm.), supra late profundeque concavo-umbilicata, subtus 

 subplana, sub lente distincte sitiraliter lineata. spira magna, utrinquc orbiter subaeciua, 

 anfr. 5-6, primi lenti, ultimus subcvlindraceus (typ. PI. libanicus W.).' Westerlund, 

 p. 120. 



Original description of Planorbis libanicus Westerlund: 'Testa magnitudine medi- 

 ocris, supra late profundeque concavo-umbilicata, infra subplana, nitida, cornea (subtus 

 paullo pallidior), firma, laevigata, sub lente forti densissime at distincte spiraliter 

 lineata ; anfr. 5^2-6, convexi, interiores utrinque perlente accrescentes, spiram magnum, 

 subaequalem formantes, ultimus major, rotundatus, subcylindraceus, supra convexus, 

 subtus pone suturam impressam obtusissime angulatus, extrorsum paullo planulatus; 

 apertura oblique rotundato-lunaris, marginibus distantibus, disjunctis, basali oblique 

 surrecto. Diam. 14, alt. ad apert. 5 mm. 



'Hab. Mons Libanon (legit beat. Evers, Havniensis). 



'Haec species forte typum novi subgeneris format, quod a subgen. Meneto differre 

 A'idetur; Testa supra late concavo-umbilicata, infra subplana, sub lente tenue distincte 

 spiraliter lineata, spira magna, utrinque subaeque lata.' Westerlund, Nach. Deutsch. 

 Malak. GeselL, 1899, pp. 170-171. 



Remarks. All of the information concerning this group name and its 

 type species is given above. No specimens for figuring have been obtain- 

 able and no figure has been published, as far as known to the writer. 

 Westerlund mentions in the description of the species (libanicus) that it 

 differs from the subgenus Menetus and that it should become the type of 

 a new subgenus, which he later calls Heterodiscus, which is unfortunately 

 preoccupied. 



