142 OXYSTYLA, SOUTH AMERICAN. 



STREBEL, Beitr. Mex. Land- und Siisswasser-Conch. v, p. 42, pi. 6, 

 f. 2 a-c. 



The obtusely angulated periphery of the last whorl and distinct 

 spiral striae seem to distinguish this form from those varieties of 0. 

 maracaibensis which have a similar " griseo-fulvescens " color, nar- 

 row varices with clear light border, and three bands or none. The 

 words " obsoletely clouded with bluish " of Pfeiffer's diagnosis should 

 be deleted, as that appearance is due to the dried soft parts, accord- 

 ing to Strebel. 



A young specimen with the type in Dohrn's collection has three 

 faint but distinct spiral bands. Strebel's specimens were received 

 with shells from the Hacha river, and in all probability came from 

 that place. The smaller one shows some faint longitudinal streaks 

 on the third and fourth whorls, which pass into spots and then disap- 

 pear farther on. The larger (fig. 48) shows a narrow peripheral 

 band of light chestnut right above the suture on the fourth and fifth 

 whorls, fading and changing to a whitish band on the last whorl ; the 

 upper band appears on the fourth whorl, is white, and continues, 

 though indistinct, to the aperture. The white part of the bands is 

 more transparent than the rest of the shell. 



0. ISABELLINA (von Martens). PI. 31, fig. 66. 



Shell ovate-conic, rather thin, very lightly striatulate, plicatulate 

 at the suture, sculptured with very close, fine spiral lines ; isabelline, 

 with pale blackish streaks and three narrow brown bands, generally 

 frequently interrupted, and with a few brownish varices. Spire conic, 

 the apex brown or white ; whorls nearly 6, a little convex, the last 

 moderately swollen. Aperture rather oblique, a little exceeding half 

 the shell's length, rhombic-oval, brownish and variegated with chest- 

 nut inside ; columella straight, thin, white ; peristome unexpanded, 

 acute, isabelline or pale brownish ; no parietal callus. 



Alt. 49, diam. 23^, length of aperture 21 J, width 13 mill. (Mts.) 

 Peru, forests of the eastern slope of the inland cordillera (Tschudi). 



Bulimus zebra var. 6 TROSCHEL, Archiv fiir Naturgeschichte 1852, 



1, p. 195. Orthalicus isabellinus von MARTENS, Binnenmoll. Vene- 

 zuela's, in Festschrift Ges. Naturforsch. Freunde Berlin, p. 191, pi. 

 1, f. 8 (1873). PFR., Monogr. Hel. Viv. viii, p. 263. 



Apparently belongs to the group of 0. ferussaci. Dr. von Martens 

 figures a smaller specimen than his measurements indicate as the size 



