372 MOLLUSCA. 
15. Physa berendti. 
Physa mexicana, var. minor and var. parva, v. Mart. Malak. Blatt. xil. p. 57 (1865) *. 
Physa heterostropha (Say ?), Strebel, Beitr. Mex. Land- und Siissw.-Conch. i. p. 54, t. 7. figg. 28, 
28 a, 29 a-z’. 
Physa berendti, Dunker (MS.), in Mus. Berol.’; Fisch. & Crosse, Miss. Scient. Mex., Mollusca, ii. 
p. 104, t. 27. figg. 14, 14a, b*. 
Physa squalida (Morelet), Pilsbry, Proc. Acad. Phil. 1891, p. 324°. 
Ovate, rather solid, often marked with a yellowish-white thickening just behind the aperture; columellar 
margin comparatively thick, ordinarily straight, but in some specimens also distinctly twisted. 
Whorls 43. 
Long. 94-14, diam. 5-8 ; apert. long. 7-8, lat. 3-33 millim. 
Hab. N.W. Mexico: Guadalajara, Tepic, and Ameca, all in the State of Jalisco 
(Richardson). 
E. Mexico: Misantla (Strebel); Rio Colipa, near the town of Colipa, in the “‘ tierra 
caliente” (Deppe & Schiede1); Rio de Octopan, also in the “ tierra caliente” 
(Deppe1); Jalapa (Deppe1, Hoge); Almolonga (Hége); Vera Cruz (Uhde*), 
on overflowed meadows and in the Laguna de los Cocos (Strebel*); Orizaba 
(Heilprin*, H. H. Smith). 
S.W. Mexico: Isthmus of Tehuantepec (Sumichrast *). 
S.E. Mexico: Tabasco (Morelet ®). 
Very variable in form, as shown by the numerous figures given by Strebel?. Although 
this species may easily be distinguished at first sight from P. osculans, var. mexicana, 
by the thickness and straightness of the columellar margin, it will be found, upon 
closer examination, that many intermediate forms occur. Irregular spiral ridges were 
observed by Strebel in some specimens, resembling those which are often found in the 
European Limnea palustris. 
Var. minima. (Tab. XX. fig. 16.) 
Physa ovalis, Wiegmann (MS.), in Mus. Berol.’, 
Physa mexicana, var. minima, v. Mart. Malak. Blatt. xii. p. 58 (1865)"; Strebel, loc. cit. p. 52, 
t. 7. fig. 26k°. . 
Similar in form to the type, but always smaller. Whorls 4—43. 
Long. 63-7, diam. 33-4; apert. long. 4-4, lat. nearly 2 millim. 
Hab. N.W. Mexico: Tepic (Aichardson). 
E. Mexico: Jalapa (Deppe®™§); Orizaba (H. H. Smith). 
A distinct thickening at the margin of the aperture seems to indicate that these 
small specimens are full-grown. Mr. Richardson collected a large number of individuals, 
all of nearly equal size. 
