126 THE NAUTILUS. 



Dr. von Ihering, who considered the group in a valuable paper* 

 has confirmed this classification. 



Having occasion lately to go over the specimens in the Acad- 

 emy collection, it became evident that the synonymy of 0. 

 bifasciata, the most widely known of them, had been made too 

 comprehensive by PfeifFer, who has been followed by subse- 

 quent authors. Certainly two, probably three species seem to 

 have been lumped ; though closely related they appear to be 

 distinct. References to the literature may be found in Manual 

 of Conchology V, p. 128 ; XI, p. 181 ; XIV, p. xxxvii, 154. 



Partial Key to species of Oxychona. 

 a Last whorl descending deeply below the keel in front ; shell 

 pitted above the keel and suture ; aperture with a rather 

 long "spout," the lip but slightly expanded above it, 

 white ; alt. 15, diam. 22 mm., between Rio and Campos, 

 Slate of Rio de Janeiro. 0. lonchostoma (Mke. ). 



a' Last whorl not descending in front. 



h. Shell higher than wide. 0. gyrina. 



b'. Shell wider than high. 



c. Lip above the angle well expanded and calloused 

 within ; outlines of spire nearl}'' straight ; peri- 

 tome white or pale pink. 0. bifasciata (Burr). 

 c'. Lip scarcely or not expanded above the angle, 

 sinuous. 



d. Peristome white or pale pink, basal margin 

 rather wide; "spout" moderately developed. 



0. bosciana (F^r. ). 

 d'. Peristome rose-colored throughout, basal mar- 

 gin narrow. Spout longer. 



0. pyramidella (Wagn.). 

 I have not seen lonchostoma, gyrina or typical pyramidella, all 

 of them described nearly a century ago, and not recorded by 

 any subsequent collector. 0. mimarum is not sufficiently 

 known to contrast with the figured species. Notes on the other 

 species and their subspecies follow. 



* Analyse der Siid-Amerikanischen Heliceen. Journ. Acad. Nat. Sci. , 

 Phila.,XV, 1912. 



