182 DRYM^US. 



Genus DRYM^EUS Albers, 1850. 



Drymceus ALB., Die Hel. 1850, p. 155. PILSBKY, Nautilus, ix,. 

 p. 114. 



Otostomus MARTENS, Binnenmoll. Venezuela's, in Festschr. 100- 

 jahrigen Feier Ges. Naturforsch. Freunde zu Berlin, p. 23 ^1873). 

 Conchol. Mittheil., ii, p. 191 ; Biologia Centrali Americana, Moll., 

 p. 191 (1893). SEMPER, Reisen ira Archip. Phil., Landmoll., p. 

 154 (1874). 



Bulimulus subgenus Goniognathmus CROSSE and FISCHER, Moll. 

 Terr. Mex., i, p. 473 (1875). 



Bulimulus, sections D, F, STREBEL, Beitr. Mex. Land und Suss- 

 wasser-Conch., v, pp. 46-48. 



Includes most species referred to Mesembrinus, Eudioptus, Mormus, 

 Navicula, Hamadryas fiemiclausaria and Liostracus by Albers and 

 others. 



Shell ovate or oblong with conic spire, umbilicate or imperforate r 

 rather thin, the aperture varying from subtriaugular to ovate, lip 

 simple or expanded, columellar margin reflexed, the apical If 

 whorls with an extremely minute even grating of longitudinal 

 and spiral lirae. 



Jaw thin, composed of subvertical, overlapping laminae soldered 

 together at their inner, free at their outer edges, generally obliquely 

 converging in the middle, leaving a triangular area of shorter laminae 

 above. 



Radula broad, with peculiarly modified teeth ; centrals tricuspid 

 or with the cusps concrescent into one ; laterals oblique, with three 

 large subequal cusps, united toward their bases ; marginals similar, 

 but with the ectocone generally split into two or three denticles. 



Genital system with a flagellum on the penis, otherwise simple. 



Type, D. hygrohylceus (Orbigny). Distribution, tropical and sub- 

 tropical North and South America. 



The references given above show that the generic term Drymceus r 

 as accepted herein, is equivalent to " Otostomus " of von Martens, 

 and to " Goniognathmus " of Crosse and Fischer. But these authors 

 based their groups upon the jaw and dentition of the snail, \\ith no 

 certain correlation of these characters with conchological criteria ; 

 and for this reason, except when dealing with the few species ana- 

 tomically known, their subgeneric or generic references were largely 

 uncertain. A natural grouping of the great mass of American 



