142 ON THE SO-CALLED PHYS OF AUSTRALIA. [Mar. 19, 
Physa. The differences, however, between its dentition and that of 
Bulinus are very cousiderable, 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 with 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 continent. 
Ameria (H. Ad., 1861) was proposed for Physe 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 :— 
Buuinus, Adans. 1757. 
Etymology. Diminutive of budle, a bubble. 
Synonyms. Isidora (Ehrenb., 1831), Diastropha (Gray, 1840), 
Ameria (H. Adams, 1861), Glyptophysa (Crosse, 1872), Pyrgophysa 
(Crosse, 1879), Physastra (Tap.-Can., 1883). 
Animal without the produced and reflected mantle-lobes of 
Physa; vadula Limnezeidan, approaching Planordis rather than Lim- 
nea; 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. 
Sheil sinistral, resembling that of Physa, acuminated or gibbous, 
smocth 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. de Conchyl. 3° sér. xii, 1872, p. 151; type pertti, Crosse, and alicie, 
Reeve. 
2 Tryon (Struct. and Syst. Conch. iii, p. 101) mentions, but I have failed to 
trace on what authority, that sinistral Limneas occur in the Sandwich Islands. 
His whole arrangement of the present group is destitute of scientific value. 
