1889.] SO-CALLED PHYS^ OF AUSTRALIA. 141 



p. 139) with the same teeth of these Bulini viiW make this clear. 

 In Planorhis the central tooth is broad-based, bicuspid, while the 

 laterals are tricuspid ; in Linmcea the central tooth is long and 

 narrow, unicuspid, while the laterals are bicuspid. A Bulinus, there- 

 fore, is not so much a sinistral Limncea as a spiral Planorbis. Further 

 research, as the animals of more species are investigated, may, per- 

 haps, bring out some points of difference leading to division into 

 subgenera of the Australian and Austro-Polynesian species. It is 

 possible that the somewhat wing-shaped form of the central tooth 

 in some cases (see figs. 2, 3, 5, 7, 8, p. 139), as compared with its 

 more regularly square shape in others (see figs. 1 and 4), may indi- 

 cate a basis of subdivision ; but at present there does not seem 

 suiRcient material to work upon. 



Finally, as regards nomenclature. 



Adanson, in 1/57, described and figured^ under the name of 

 Le BuUn or Bulinus a small sinistral freshwater shell from Senegal, 

 length 1 1 lines, breadth | line. The shell is evidently not adult, 

 but the description and magnified drawing of the animal, which 

 shows none of the produced mantle-lobes of a true Physa (indeed, 

 Adanson fortunately remarks, " le manteau tapisse tout I'interieur 

 de la coquille sans sortir au-dela des bords de son ouverture "), are 

 sufficient to enable us to recognize it as belonging to the genus now 

 under investigation. Fischer, therefore, is quite right in adopting 

 Bulinus as the generic name'. 



Isidora (Ehrenb. 1831) is a synonym, see Jickeli, loc. supr. cit. 



Fischer, in his ' Manuel,' goes on to enumerate five subgenera, 

 viz. Pyrgophysa, Plesiophysa, Ameria, Glyptophysa, and Physopsis. 



Pyrgophysa was proposed by Crosse' for Ph. mariei, Crosse, 

 from Nossi-Be, on the ground of its turreted spire. But this sub- 

 genus is of little value, as the Australian species present every 

 variety of such formation. Crosse's description of the shell (" baud 

 nitens, vestimento opaco induta") makes it plain that it belongs to 

 this genus. 



Plesiophysa (Fischer, 1883) includes the remarkable Ph. striata, 

 d'Orb., from Guadeloupe. This must be the ' Physa sp.' from Point 

 a Pitre*, the radula of which is described by Bland and Binney^ 

 as follows : — " Central tooth 5-cusped, central of these the largest ; 

 laterals 4-cusped, one inner, large, stout ; marginals a reproduction 

 of the laterals." This description at once removes the species from 



^ Senegal, pp. 5-7, pi. fig. g. ii. 



- Yet he remarks : " Etymologie inconnu." Adanson, however, I.e., seems 

 to make it fairly clear when he says :— " Oette denomination m'a paru lui con- 

 veuir, parce que I'animal pendant sa Vi& nage presque continuellement a fleur 

 d'eau, et qu'apres sa mort la coquille flotte comme une petite hulle d'air trans- 

 parente." 



■' Journ. de Conchyl. 3" ser. six. 1879, pp. 208-209 ; xx. 1880, pp. 141-142, 

 pi. iv. fig. f>. 



' Maze (Journ. de Conchyl. .3° ser. xxiii. 1883, pp. 30-31) records Plesiophysa 

 striata from Point a Pitre. 



5 " Note on a cui-ious form of lingual dentition in Physa," Ann. Lye. N. H 

 N. York, X. 1873, pp. 255-257, pi. xi. figs. 2, 3. 



