250 SOUTH AMERICAN OBELISCl S. 



This small species is remarkable for its very large, obtuse 

 summit and the straight spire, not in the least attenuate 

 above, being convex rather than contracted there. It was 

 sent by Moricand to R. Swift as B. sylvaUcus Spix, and is 

 probably from the province of Bahia. It is a stouter species, 

 with a far larger summit, than B. clava Rve., the habitat of 

 which is unknown. I have not been able to compare it with 

 typical 0. haplostylus Pfr., which seems to be related. Some 

 specimens are a little more slender than the type, 28 x 7.8 

 mm., aperture 8.8 mm. 



7. 0. BACTERIONIDES (Orbigny). PL 36, figs. 71, 72. 



Shell very long, turrite, subcylindric, thin, transparent, 

 smooth, whitish or amber-colored. Spire obtuse. Whorls 9, 

 flattened. Aperture nearly quadrangular, narrowed above 

 and below; columella straight, acute, truncate; lip thin. 

 Length 17 [or 14?], diam. 4 mm. Animal very long, yel- 

 lowish (Orb.}. 



Bolivia : arid hills of the Rio Grande, provinces of Laguna 

 and Valle Grande, at the last foot-hills of the Andes, chiefly 

 at a place called Pampa Ruis, under stones (Orb.) ; San Pedro 

 Paraguay (Borelli). 



Helix bacterionides ORB., Mag. de ZooL, 1835, p. 9. Buli- 

 mus b., ORB., Voy. dans 1'Amer. Merid., p. 260, pi. 29, f. 1-3. 

 -PFR., Mono'gr., ii, p. 156 ; iii, p. 393 ; Conchyl. Cab., p. 117, 

 pi. 35, f. 15-17. DESK, in Per., Hist,, ii, p. 116, pi. 142 a, f. 

 12-14. Subulina b., ANCEY, Boll. Mus. Zool. ed Anat. Comp. 

 R. Univ. Torino, xii, no. 309, p. 6 (1897). 



"This species is very close to B. octonus, but differs tren- 

 chantly by the flattening of the whorls, rendering the mouth 

 angular instead of rounded; it is also less conic and 

 smoother, otherwise having the same appearance and char- 

 acters" (Orb.). 



No columellar truncation can be traced in d 'Orbigny 's 

 figure, which I have copied. Pfeiffer, who probably had 

 authentic 'specimens, states that it is imp erf orate, and the 

 columella is somewhat callously twisted above. He gives the 

 linu-nsions as 14x4 mm. The "17" of Orbigny 's descrip- 



