DRYM^EUS LEIOSTRACUS. 91 



straight-sided, the lip narrowly expanded, surface smooth, without 

 spiral striae; protoconch with excessively fine spiral striae, but no 

 vertical sculpture except occasionally some coarse, low, hardly notice- 

 able wrinkles. Type D. vittatus Spix. 



The species are illustrated on plate 14. 



Distribution, eastern Brazil. Habits arboreal. 



Leiostracus^ as defined by Albers and retained by von Martens and 

 other authors, was a. heterogeneous mass of thin-lipped species from 

 both North and South America. As here restricted, it includes a 

 very natural group of tree snails dominant in the Province of Bahia, 

 Brazil, remarkable for their almost smooth apical whorls, straight- 

 sided and pyramidal spires, and usually conspicuous band or stripe 

 pattern of coloration. The anatomy of the group is wholly unknown ; 

 and it is placed under Drymceus as a subgenus mainly on account of 

 the general appearance of the shell. 



The apical whorls in vittatus, onager, vimineus, manoeli, cinna- 

 momeolineatus and perlucidus show no fine vertical sculpture, but only 

 spiral striae, very fine and close, usually more or less interrupted by 

 shallow rugosities of the surface, and often wholly effaced in adult 

 shells by superficial erosion. D. obliquus, which I have not seen, is 

 said by Dohrn to have a " ganz fein gegittertes Embryonalende" 

 This indicates the close alliance of that species to Drym&us, and 

 perhaps its removal from Leiostracus. 



As naturalists now generally adopt the principle that a name 

 should be written as its author wrote it, even when the customary 

 system of transliteration from Greek to Latin has been transgressed, 

 it would seem that Leiostracus may stand, though there is an earlier 

 generic term Liostraca, of the same derivation and significance. 



D. VITTATUS (Spix). PI. 14, figs. 1, 2, 3, 4, 5. 



Shell umbilicate, oblong-turreted, thin but moderately strong; 

 yellow or corneous-buff, unicolored or variously banded or streaked 

 with dusky reddish brown. Surface glossy, smooth, the growth- 

 striae faint. Spire long conic, with straight lateral outlines, the apex 

 rather obtuse. Whorls 7 to 8, moderately convex, the last well 

 rounded at the periphery and below ; sutures impressed. 



Aperture oblique, colored within like the outside ; peristome white, 

 thin, decidedly but very narrowly expanded at the edge, the outer 

 lip more arcuate above, basal lip well rounded, columellar margin 



