148 OXYSTYLA, SOUTH AMERICAN. 



the first one black-tipped, nearly planorboid, the earlier two or three 

 smooth except for short low folds just above the suture, the following 

 whorls moderately convex. 



Aperture somewhat oblique, rather small, purple-tinted, white in- 

 side; peristome simple, broadly bordered with purple-brown inside 

 and out, columella subvertical, rather long, slightly convex, or some- 

 what calloused, white or dark chestnut colored ; parietal callus 

 chestnut. 



Alt. 62, diam. 30, longest axis of aperture 27J mill, (specimen). 



Alt. 85, diam. 40 mill. (Crosse). 



Banks of the Amazon (Reeve); Upper Amazon (Orton); Mission 

 of Sarayacu, Peru (Castelnau); Napo, Ecuador (Martinez). 



Bulimus ( Orthalicus) adamsoni (Gray), BECK, Index, p. 60 ( 1837). 

 Helix (Cochlitoma) regina var. P minor, FERUSSAC Tabl. p. 49; 

 Histoire, pi. 119, f. 1, 2. Bulimus bensoni REEVE, Conch. Icon. pi. 

 78, f. 571 (Sept., 1849). PFR., Monogr. iii, p. 388; viii, p. 261; 

 Conchyl. Cab. p. 75, pi. 21, f. 1. HUPE in Castelnau's Exped., p. 

 31. Orthalicus bensoni SHUTTLEWORTH, Notitise Mai. p. 60, pi. 4, 

 f. 3, 4, 5 CHENU, 111. Conch, i, p. 439, f. 3225 HIDALGO, Journ. 

 de Conchyl. 1870, p. 64; Viaje al Pacifico, Mol., p. 133, pi. 7, f. 13. 

 CROSSE, Journ. de Conchyl. 1871, p. 318. Zebra bensoni MILLER, 

 Malak. Blatter xxv, p. 186. COUSIN, Bull. Soc. Zool. France xii, 

 p. 198. 



The long spire with large, rather mammillar apex, the three articu- 

 lated girdles, and the fine but strong decussation of the surface are 

 characteristic. There is a single variceal purple-brown streak on the 

 penultimate whorl of the specimen drawn in fig. 62; one of Shuttle- 

 worth's illustrations shows a similar stripe, and Fe~russac's shell has 

 one. The pattern varies, some specimens having narrow, others 

 wide stripes, and the greenish-yellow cuticle of some shells is largely 

 wanting, or very thin and pale yellow below on other specimens, 

 otherwise in good condition. The large specimen from Napo (length 

 80, not 85 mill.), commented on by Hidalgo (fig. 65) has "a callos- 

 ity superimposed upon the columella, as in 0. regina, and due with- 

 out any doubt to advancing age." This group of Oxystyla certainly 

 approaches Corona in the convex form of the columella. 



This species was noticed first by Ferussac, who considered it a 

 small form of his H. regina, and figured it on the plate of that spe- 

 cies. Beck, in 1837, gives the name "0. adamsoni (Gray) B." to 



