126 OXYSTYLA, MEXICO, ETC. 



coloration of the tip does not coincide with the more or less numerous 

 streaks on the last whorl ; but in the specimens with spiral bands the 

 dark color of the tip is rather more extended. The sculpture usually 

 consists of spiral striae only ; but in several specimens numerous mal- 

 leated impressions are also visible, sometimes in rows descending 

 towards the aperture. The dimensions given above are taken from 

 a most typical example of middle size ; the largest specimen measures 

 58, 30 and 29 millim., but it is one of those which approach 0. zoni- 

 ferus. The variety b shows a prevalent dark coloration of the tip, 

 the last whorl, and the aperture, together with a spiral band which 

 is constantly present in the first half of the last whorl. The var. c 

 may be termed an albino specimen, the brown color being very pale 

 in the callus of the aperture, and wanting altogether at the tip and 

 on the external edge of the aperture. In short, these twenty-two 

 specimens prove that it is very difficult, or rather impossible, to trace 

 clear and precise specific distinctions in this genus." (Martens.) 



O. LONGA (Pfeiffer). PI. 21, figs. 33, 34 ; pi. 22, all figs. 



Shell elongate-conic or ovate-conic, rather thick and strong, white, 

 or yellowish on the last whorl, boldly marked with black-brown or 

 purplish-black stripes which are usually straight on the body-whorl, 

 irregularly flexuous on the spire, and are often narrowly bordered 

 with rust-reddish ; varices prominent, broad, black, often bordered 

 behind by a blue-gray stripe, and usually 4 to 6 on the whole shell, 

 3 or 4 frequently being upon the last whorl. A narrow brown band 

 sometimes appears just above the suture on the spire. Surface nearly 

 lustreless, with rather coarse growth-wrinkles, and subobsolete, mi- 

 nute, irregular spiral stria?. Whorls 6^ to 7, the earlier ones slightly, 

 the last two strongly convex. Apex obtuse, white or black. 



Aperture small in the typical form, very oblique, ovate, white with 

 black or purple stripes at the positions of the varices within ; peri- 

 stome simple, broadly black bordered outside and within ; columella 

 short, concave, wholly black, or white-edged ; parietal callus black- 

 brown. 



Alt. 56, diam. 30.4, alt. of aperture 26.1 mill. (Pfeiffer's type.) 



Alt. 60, diam. 31, longest axis of aperture 32 mill. 



Alt. 56, diam. 27^, longest axis of aperture 28 mill. 



Localities for forms referred to 0. longa (the type locality of which 

 is unknown) : Central Mexico : State of Michoacan, especially at 



