PSEUDOSUBULINA. 7 



11. P. ORIZABENSIS Pilsbry, n. sp. PI. 2, fig. 26. 



Shell imperforate, turrite, slender, thin, whitish corneous, 

 glossy. Sculptured with thread-like vertical riblets which 

 distinctly project above, denticulating the suture. On the 

 last three whorls these riblets are widely and unequally 

 spaced, with some fine strise in the intervals ; on earlier whorls 

 the riblets are finer, regular and much more crowded. The 

 first l 1 /^ whorls are smooth, the next whorl very finely striate. 

 The base of the last whorl is striate but not ribbed. The out- 

 lines of the spire are nearly straight, but a little concave near 

 the obtuse summit. Whorls 9, moderately convex. Aperture 

 small, subvertical. Columella simple and vertical, with re- 

 flexed and adnate edge. Length 8, diam. 2.2, aperture 2.1 mm. 



Mexico: Orizaba, State of Vera Cruz (Heilprin Exped. 

 1890). Type 61545 A. N. S. P. 



Pseudosubulina (Volutaxis) miradorensis PILS., Proc. A. 

 N. S. Phila. 1891, p. 312 ; cf. Martens, Biologia p. 639. Not 

 V. miradorensis Strebel. 



The widely spaced riblets, producing small but distinct 

 denticulations along the suture, are the most prominent fea- 

 ture of this species, which I formerly mistook for S. mira- 

 dorensis Strebel. 



12. P. IRREGULARIS Pilsbry, n. sp. PL 6, fig. 24. 



Shell imperforate, turrite, thin, whitish-corneous, sculp- 

 tured with very irregularly spaced unequal, subvertical 

 thread-like riblets, wanting on the firsit l 1 /^ whorls and very 

 weak on the base of the last whorl. Apex obtuse. Whorls 

 10, moderately and equally convex. Aperture small, rhombic- 

 ovate, subvertical. Columella straight and vertical, very 

 slightly and inconspicuously excavated at the; base. Length 

 9, diam. 2.2, length of aperture 2.2 mm. 



Mexico: Texolo, State of Vera Cruz (S. N. Rhoads, 1889). 



Chiefly characterized by its very irregularly spaced rib- 

 lets. Five specimens were taken. 



13. P. BOREALIS (Pilsbry). PI. 6, figs. 21, 22. 



Shell wholly imperforate, turrite, very slender and long, 



