ORTHALICUS. 187 



selecting the same species, clearly fix the type of Beck's genus; 

 although Herrmannsen a year or two later gives B. zebra Mull., as 

 type of the group, a decision accepted by Dr. von Martens in 1860, 

 and by some later authors. 



Shuttleworth, in 1852, published a monograph of the genus, which 

 like ail of his conchological work is a model of lucid reasoning ; and 

 this work established most of the species then known upon a firm 

 basis so far as their synonymy was concerned. He divided Ortha- 

 licus into three sections: SULTANA for 0. gallina-sultana and its allies, 

 ZEBRA for the undatus group, and CORONA for the regina group. 

 Further, he proposed a subgenus, PORPHYROBAPHE, for the species 

 with thickened or reflexed lip. These divisions have been retained 

 by authors generally up to this time. MM. Crosse and Fischer, in 

 discussing the genus in their volume on land mollusks in the " Mis- 

 sion Scientifique an Mexique," take occasion to review the classifica- 

 tion, endorsing Shuttleworth's conclusions. Finally Herr Strebel 

 has offered some suggestions of value for the improvement of Shuttle- 

 worth's classification, in that veritable mine of observation and original 

 suggestion, the * Beitrag zur Kenntniss der Fauna Mexikanischer 

 Land- und Susswasser-Conchylien." His chief modification is in 

 proposing the definite separation of the Porphyrobaphe species with 

 pitted, from those with smooth, nuclear whorls. 



Key to groups of Orthalicus. 



a. Shell thin, capacious, with oblique large aperture and simple 

 and thin or somewhat thickened lip and columella, the former 

 unexpended. Section ORTIIAI.ICUS s. sir. (see below, p. 188.) 

 a 1 . Shell solid, more lengthened, the aperture smaller, but slightly 

 oblique or vertical, the lip thickened and blunt, or expanded or 

 reflexed; columella usually with one or two folds. Section 

 METORTHALICUS Pilsbry. 



b. Shell very solid, with the lip thick, expanded or not, some- 

 what purple or broadly purple-bordered within. Colom- 

 bian. Group of 0. atramentarim, p. 205. 

 b 1 . No purple border within the lip, and without the above 

 combination of characters. Species of Ecuador and Peru. 

 c. Shell spirally striated ; peristome white or pale. 

 d. Spaced, rather strong spiral lines or furrows, 



