PHYSA. 373 
Var. lacustris. 
Physa lacustris, Clessin, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Limnziden, p. 344, 
t. 48. fig. 9°. 
Very small, with short obtuse spire. 
Hab. E. Mexico: Lake Coatepec 9. 
Var. intermedia. 
Physa berendti, var. intermedia, Fisch. & Crosse, loc. cit. p. 104, t. 39. figg. 7, 7a, 6”. 
With more prolonged spire and less thickened columellar margin; a reddish thickening behind the margin of 
the aperture. 
Hab. S. Centrau Mexico: Putla, State of Oaxaca (Sallé 1°). 
This form seems to me to be nearer to P. osculans than to P. berendti. 
16. Physa squalida. 
Physa squalida, Morelet, Test. Noviss. ii. p. 16 (1851)1; Tate, in Am. Journ. Conch. v. p. 158 
(1870)*; Fisch. & Crosse, Miss. Scient. Mex., Mollusca, ii. p. 105, t. 30. figg. 14, 14a°; 
Clessin, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Limneziden, p. 334, t. 47. fig. 1*. 
Hab. S.E. Mexico: in swamps of the river Usumacinta, near Balancan, State of 
Tabasco (Morelet | 3), 
CrntraL Nicaragua: pools bordering the Lake of Nicaragua, at Grenada (Tate *). 
E. Nicaragua: in a creek of the Rio San Juan, Toro Rapids (Tate ?). 
Fischer and Crosse distinguish this species from P. berendti by the elongate spire 
and the absence of a thickening in the margin of the aperture; they quote for it also. 
Strebel’s fig. 28, taken from a specimen from Vera Cruz. But as this latter shows a 
distinct thickening in the margin, it is safer to leave it with P. berendti, as Strebel has 
done, and limit P. sgualida to the more southern regions. I have not seen a specimen 
from Tabasco. 
Fischer and Crosse? also mention Costa Rica, without nearer indication, as a locality 
for P. squalida, on the authority of Sallé; this Costa Rican shell probably belonged 
to P. polakowskyt. 
17. Physa strebeli. 
Physa osculans, var. minor, v. Mart. Malak. Blatt. xii. p. 58 (1865) °. 
Physa, sp., Strebel, Beitr. Mex. Land- und Stissw.-Conch. i. p. 53, t. 6. figg. 27, 27 a, 6 (1873) *. 
Physa strebei, Crosse & Fisch. Journ. de Conch. xxix. p. 335 (1881)°; Miss. Scient. Mex., 
Mollusca, ii. p. 103 *. 
A more solid shell than P. osculans, with deep sutures and a thickened lip at the aperture. 
Hab. E. Mexico: Vera Cruz (Uhde, in Mus. Berol.1); in a ditch outside the wall of 
the town of Vera Cruz (Strebel 2~*). 
