184 DRYM^EUS. 



was therefore a direct, though doubtless unintentional, violation of an 

 essential rule of nomenclature, everywhere adopted. 



Otostomus therefore must be restricted to the species signatus. 

 Whether this will prove to have the anatomical peculiarities of 

 Auris, or be similar to Drymceus, is hardly a proper subject for hypo- 

 thesis. Should the latter prove to be the case, I would elevate 

 Otostomus to generic rank, as it has conchological peculiarities quite 

 sufficient to separate it -from Zaplagius or Drymceus. 



The distribution of Drymceus, while very wide, is still noticeably 

 less extended than that of the parent genus Bulimulus. To the 

 southward, Chili and the Argentine Republic are almost destitute of 

 species ; and in the north, Florida and the southern border of Texas 

 are its extreme limits. The West Indies have a few species; but 

 such outlying areas as Lower California, the Galapagos Islands and 

 Fernando Norouha, have apparently not been reached. In general, 

 the group is a continental one, nesiotes being few. 



The species of Drymceus are largely arboreal, and probably all 

 the polychromatic forms live habitually off the ground; but there 

 are also numerous species, especially in the Peruvian Andes, which 

 live on the ground, under cacti, stones, etc. 



Numerous subgenera have been proposed, some of them superflu- 

 ous. The following may be retained. 



* Apical sculpture typical, an even grating throughout. 



a. Oater lip expanded or reflexed. 



ZAPLAGIUS. Shell conic or obliquely conic, with a keel around 

 the truncate or flattened base, which is subperforate and rimate; 

 last whorl ascending in front. 



DRYMCEUS. Shell ovate or oblong, smoothish, generally very 

 light colored, with or without chestnut or blackish variegation. 



b. Outer lip unexpanded, simple. 



MESEMBRINUS. Shell oblong-ovate or oblong-pyramidal, gener- 

 ally perforate or rimate ; columella straightened. 



EUDIOPTUS. Shell ovate or oblong, very thin, translucent and 

 fragile, imperforate or nearly so, the columella arcuate, thread-like; 

 unicolored corneous. 



STENOSTYLUS. Shell ovate, very thin, imperforate or nearly so, 

 the columella arcuate and very slender; streaked or dark colored. 

 Forms resembling Plectostylus in appearance, but unspotted, with 

 typical Drymceus apical sculpture. 



