| 100 MOLLUSCA. 
In its glossy lustre and in general form 8. physodes resembles the shells of the 
genus Physa, especially P. rivalis from the West Indies. 
Pfeiffer mentions a larger variety (long. 15, diam. 7 millim.), from Chiapas, which 
seems to be also somewhat different in colour, as he calls it “‘ pallida ;” itis unknown 
to me. 
The columella is remarkably thick and strongly twisted in full-grown specimens, but 
rather thin and nearer to the perpendicular direction in younger ones. 
Pfeiffer’s description of S. awriculacea™ agrees very well with large individuals, and 
deserves scarcely the name of a variety. 
26. Streptostyla limneiformis. (Tab. V. fig. 24, var.) 
Spiraxis limneiformis, Shuttl. in Bern Mittheil. 1852, p. 207 (Diagn. no. 2, p. 26)*; Notitiz 
Malae. ii. p. 15, t. 5. fig. 8°; Pfr. Monogr. Helic. Vivent. iti. p. 476 °. 
Spiramis limneiformis, v. Mart. in Albers’s Die Helic. ed. 2, p. 34°. 
Streptostyla limneiformis (Shuttl.), Fischer & Crosse, Miss. Scient. Mex., Mollusca, i. p. 38°. 
Hab. E. Mexico: Cordova (Jacot-Guillarmod 1°). 
Fischer and Crosse think it is probable that this species is based on specimens which 
are not full-grown. ; 
Var. parvula. (Fig. 24.) 
Spiraxis parvula, Pfr. P. Z. S. 1856, p. 379°; Malak. Blatt. i. p. 284 (1856) " ; Monogr. Helic. 
Vivent. iv. p. 579°. 
Streptostyla parvula (Pfr.), Fischer & Crosse, loc. cit. p. 57°. 
Hab. Cutapas (Ghiesbreght °°). 
In Pfeiffer’s collection there is a specimen from Chiapas, marked “ parvula, var.,” 
which is a little larger than the type (length 9, breadth 4, aperture 5 millim., instead 
of 8, vix 4, and 4%) and wants the reddish band at the suture; it is marked with rather 
deep lines of growth and-in general form and appearance much resembles 8S. limnei- 
formis, but is considerably smaller. 
27. Streptostyla oblonga. 
Spiraxis oblonga, Pfr. P.Z. 8. 1856, p. 378'; Malak. Blatt. iii. p..283 (1856) >; Monogr. Helic. 
Vivent. iv. p. 579°, 
Streptostyla oblonga, Fischer & Crosse, Miss. Scient. Mex., Mollusca, i. p. 57 *. 
Hab. Cutapas (Ghiesbreght 1*). 
Known to me only by Pfeiffer’s description. 
