DRYM^US-ZAPLAGIUS. 185 



* * Apical sculpture obscure, the longitudinal elements predominating 



above, spiral below on each whorl. 



LIOSTRACUS. Shell pyramidal, glossy, conspicuously colored, the 

 outer lip somewhat expanded. 



Of these groups, all seem to be natural assemblages ex cept Mesem- 

 brinus, which integrades through numerous diverse species with 

 Drymceus. It is here retained in its present limits for convenience. 



Subgenus ZAPLAGIUS Pilsbry, 1896. 



NaviculaSpix, Testae. Bras., p. 22 (in synonymy), pi. 15, type 

 Navicula fasciata Bp\=.Helix navicula Wagner (1827). Not JVaw- 

 cula DE BLAINV., Diet. Sci. Nat., xxxiv, p. 319 (1825) ; see also 

 " Les Navicules " Blainv., Man. de Malac., p. 535, and Diet. Class. 

 d'Hist. Nat., xi, p. 472 (1827), a subgenus of Area. Otostomus 

 BECK (in part), Index Moll., p. 55, and of many subsequent authors. 

 .Not Otostomus as restricted by Gray, see vol. X, p. 107. Zaplagius 

 PILS., Nautilus ix, p. 115, February, 1896. 



Conic or obliquely conic Bulimulidse with typical Drymceus apical 

 sculpture (pi. 25, fig. 62), a keel around the truncate or flattened 

 base, subperforate and rimate, the last whorl ascending in front, the 

 lip expanded or reflexed, aperture triangular or ear-shaped. Radula 

 with enormously broad mesocones on central and lateral teeth ; jaw 

 deeply arched, with narrow plaits strongly converging mesially. 

 Type D. navicula. Distribution, Province of Bahia to Rio Janeiro, 

 Brazil. 



From Otostomus (type signatus Spix), the present group is distin- 

 guished by the absence of heavy apertural callosities; from typical 

 J)rymceus by the flattened base of the shell and broad mesocones 

 accompanied by much reduced side cusps of the teeth. 



The Andean species resembling Zaplagius somewhat in form of 

 the shell, such as D.fallax Pfr., are of wholly different genesis, being 

 a slight modification of typical Drymceus. Recognizing this, Pfeiffer 

 has proposed for one of them the subgeneric name Semiclausaria f 

 i)ut when the whole series is seen, this term seems superfluous. 



Key to species. 



I. Diameter of the obliquely-conic shell exceeding the alt. 



a. Outer lip inserted on or above the penultimate whorl ; 

 basal lip subhorizontal. 



