MEXICAN OPEAS. 213 



"This little species is chiefly characterized by the riblets 

 observable on some of the whorls of the spire, usually the 

 third and fourth, and which wholly disappear on the last 

 or penultimate whorls " (C. & F.). 



19. 0. BOCOURTIANUM (Crosse et Fischer) . PI. 29, figs. 87, 88. 

 Shell imperforate, subelongate-turrite, thin, translucent, 



slightly striatulate, nearly smooth, pale corneous- whitish. 

 Spire long, the apex obtuse; suture impressed. Whorls 8, 

 rather flattened, the embryonic 2 smooth, whitish, the last 

 whorl much shorter than the spire (as 2 to 7). Aperture 

 subvertical, oblong-oval; peristome simple, unexpanded, the 

 margins remote, columellar margin a trifle dilated, basal and 

 outer margins acute. Length 9, diam. 2, aperture 2 x 1.25 

 mm. (C.&F.). 



Guatemala: Province of Vera Paz (Bocourt; Paris Mus.) r 

 in stomach of Glandina plicatula. 



Stenogyra bocourtiana C. & F., Journ. de Conchyl. xvii, 

 1869, p. 424. Bidimus &., PFR., Monogr. viii, p. 136. Opeas 

 &., C. & F., Moll. Mex. p. 602, pi. 26, f. 8. MARTENS, Bio- 

 logia, Moll., p. 292, with va-r. pittieri, pi. 17, f. 6 (1898). 



"Distinctly broader and more conical than 0. subula." 



Var. pittieri Martens. PI. 29, fig. 90. 



"Somewhat broad, glossy, diaphanous, distinctly striate; 

 whorls a little more convex, 7 only; general shape as in 

 0. bocourtianum; umbilicus almost closed, punctiform; colu- 

 mella somewhat twisted. Length 10, diam. 3, aperture 3.5 x 2 

 mm." (Martens). Central Costa Rica at La Palma, 1500 

 meters above the sea, beneath tuna plants (cactoids). 

 (Pittier) . 



20. 0. GUATEMALENSE Strebel. PI. 29, fig. 91. 



Shell rather strong, rather glossy, light yellowish corneous 

 and translucent. The sculpture consists of somewhat irregu- 

 larly strong, very fine, closely crowded folds. The first l 1 ^ 

 whorls form a 'cupola, the following increase in width very 

 slowly, -are but little convex, and are weakly step-like at the 

 deep suture; the last has a weak callus deposit on the aper- 



