142 ON THE SO-CALLED PHYS^ OF AUSTRALIA. [Mar. 19, 



Physa. The differences, however, between its dentition and that of 

 Bulinus are very considerable, the central tooth being 5-cusped, 

 cusps sharp, instead of 2-cusped, cusps blunt, the extreme marginals 

 being similar in character to the laterals, instead of entirely different, 

 with no trace of serration. Further, the occurrence of the species 

 on an island in the Antilles raises a difficulty on the score of distri- 

 bution, if its close connection vi'iih Bulinus be pressed. It seems, 

 therefore, better on every ground to separate off Plesiophysa, in the 

 expectation that its congeners will hereafter be found rather on the 

 South-American than the African contioent. 



Ameria (H. Ad., 1861) was proposed for Physce with keeled 

 whorls, e. g. P. alicia, Reeve. The distinction is untenable. Every 

 gradation of keeling is observable in the Australian Bulini, and 

 occasionally the same species is indifferently keeled or perfectly 

 smooth. 



Glyptophysa (Crosse, 1872 \ not 1870; Fischer, 'Manuel') was 

 meant for similar shells, and must share a similar fate. 



Physopsis (Krauss, 1848) has a truncated columella and lustrous 

 shell. Fischer regards it as a subgenus of Bulinus, but it does not 

 appear that the animal has ever been investigated. There is nothing, 

 therefore, to show that it belongs to Bulinus rather than to Physa. 



Physastra (Tapp.-Can., 1883) has been dealt with above. 



Thus reorganized the genus will read as follows : — 



Bulinus, Adans. 1757. 



Etymology. Diminutive of bulle, a bubble. 



Synonyms. Isidora (Ehreub., 1831), Biastropha (Gray, 1840), 

 Ameria (H.Adams, 1861), Glyptopliysa (Crosse, 18/2), Pyrgophysa 

 (Crosse, 18/9), Physastra (Tap. -Can., 1883). 



Animal without the produced and reflected mantle-lobes of 

 Physa ; radula Limnseidan, approaching Planorbis rather than Lim- 

 ncea ; central tooth bicuspid ; cusps rather blunt, base square ; 

 laterals tricuspid ; marginals serrate. Laterals about 6 to 10, mar- 

 ginals about 25 to 33. Number of rows varying between 140 and 

 220. 



Shell sinistral, resembling that of Physa, acuminated or gibbous, 

 smooth or keeled ; texture somewhat thick, covered with a deciduous 

 epidermis ; columella strong, often reflected ; umbilicus sometimes 

 very wide and deep. 



Distribution. Australia, Tasmania, New Zealand, New Guinea, New 

 Caledonia, Viti and Tonga Islands ; Africa, N., N.E., W., and S. ; 

 S. France, Spain, and all countries bordering the Mediterranean". 



? Subgenus Physopsis (Krauss, 1848). Animal unknown ; shell 

 with truncated columella. 



Distribution. Natal. 



1 Journ. do Conchyl. 3" s6r. xii. 1872, p. 151 ; tjfepetiti, Crosse, and alicia, 

 Eeeve. 



- Try on (Struct, and Syst. Conch, iii. p. 101) mentions, but I bare failed to 

 trace on wliat authority, that sinistral Lironseas occur in the Sandwich Islands. 

 His whole arrangement of the present group is destitute of scientific value. 



