326 COCHLICOPA. 



1901, p. 37 (1901). Cochlicopa davidis MLLDPF. Ann. Mus. 

 Zool. de 1'Acad. Imp. Sci. St. Petersb. vi, 1901, p. 389. 



"It is quite constant in size as well as in the several other 

 characters enumerated above, which seem to me sufficient to 

 give this Zua specific rank" (Ancey). 



"Always easily recognized by the slower increase of the 

 whorls, narrower shape and smaller aperture" (Mlldff.). 



For the occurence of davidis 'or a similar form on Sado 

 Island, see p. . 



3. C. SINENSIS Heude. PI. 48, figs. 23. 



Shell, small, with smooth glossy epidermis; spire conic-acu- 

 minate ; whorls 7, oblique, regular. Aperture oval ; peristome 

 simple, thick, continuous, interrupted at the external sinus. 

 Length 7, diam. 2 mm. (Heude.} 



China: Prov. Sytshuan at Tsheug-hou (Heude); Tapa; 

 valley of the Tung (Mlldff.). 



Zua sinensis HEUDE, Notes sur les Moll. terr. de la Vallee 

 du Fleuve Bleu, pt. 3, 1890, p. 151, pi. 35, f. 17. Cochlicopa 

 sinensis MLLDPF, Ann. Mus. Zool. Acad. Imp. Sci. St. Petersb. 

 vi, 1901, p. 389. 



"Very small and slender, the aperture smaller than in the 

 preceding [C. davidis] 11 (Mlldff.). 



This form and the preceding are admitted as species in 

 deference to the opinion of von Moellendorff, but they are 

 certainly very closely related to some forms of C. liibrica. 



4. C. THALASSINA (Jousseaume) . PL 52, fig. 1. 



Shell imperforate, minute, elongate, fragile, diaphanous, 

 polished, whitish; spire produced, regularly tapering-cylin- 

 dric, a little obtuse at the summit. Whorls 6 to 7, a little con- 

 vex, regularly increasing, separated by a slightly impressed 

 suture, the last whorl convex. Aperture vertical, ovate ; peris- 

 tome acute, slightly spreading and a little thickened within; 

 columellar margin a little arcuate, slightly thicker: outer 

 margin a trifle arching forward; margins joined by a very 

 thin callus. Length 2.25, diam. 1, aperture 0.75x0.5 mm. 

 (Jouss.) . 



