406 BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



1859. Helicostyla dimera Pfeiffer, Monographia heliceorum viventium, vol. 4, 



p. 198. 



1860. Helicostyla dimera Martens, Albers, Die Heliceen, ed. 2, p. 175. 



1868. Helix dimera Pfeiffer, Monographia heliceorum viventium, vol. 5, p. 267. 

 1877. Cochlostyla dimera Semper, Reisen im Archipel der Philippinen, pt. 2, vol. 3, 



p. 187. 

 1887. Cochlostyla dimera Hidalgo, Journ. Conchyl., vol. 35, p. 141. 

 1892. Cochlostyla dimera Pilsbry, Man. Conch., ser. 2, vol. 7, p. 156, pi. 30, figs. 



29, 30. 

 1895. Helicostyla dimera Pilsbry, Man. Conch., ser. 2, vol. 9, p. 223. 



1897. Helix dimera Hidalgo, Journ. Conchyl., vol. 44, pp. 245, 279, 290, 331, 332, 



340, 349, 351. 



1898. Cochlostyla dimera Mollendorff, Abh. Naturf. Ges. Gorlitz, vol. 22, p. 



122; in part. 

 1901. Cochlostyla dimera Hidalgo, Obras malacologicas, pt. 1, pp. 481-482 (in 



part), pi. 48, fig. 8. 

 1910. Helix dimera Mollendorff, Kobelt, and Winter, Semper's Reisen im 



Archipel der Philippinen, vol. 10, pp. 203-204 (in part), pi. 41, figs. 4, 



4a, 5. 

 1932. Cochlostyla {Helicostyla) dimera Bartsch, Journ. Washington Acad. Sci., 



vol. 22, p. 336. 



Shell broadly ovate, covered with a very thin pale olive-yellow 

 periostracum, which is usually absent on the early turns. When the 

 periostracum is removed the nuclear whorls are brown, while the 

 succeeding turns are also brown but gradually become paler, passing 

 through a rosy tinge to white. A moderately dark brown band is 

 present at the summit and another immediately posterior to the 

 periphery with the space between flesh-colored. This color scheme 

 terminates abruptly at the periphery of the last whorl, from there 

 anteriorly to the umbilical area. The broad base is chocolate-brown, 

 which is also the color of the outer lip, while the columella is flesh- 

 color except at the extreme tip, which is chocolate-brown. The 

 interior of the aperture is divided in its color scheme between bluish 

 white posteriorly and chocolate-brown basally. The 1.6 nuclear 

 whorls are moderately elevated, well rounded, and marked by incre- 

 mental lines only. The postnuclear whorls are moderately well 

 rounded and marked by fine, retractively slanting, incremental lines, 

 which are almost threadlike, and numerous microscopic spiral stria- 

 tions on both spire and base. The aperture is almost subcircular, 

 oblique; outer lip slightly expanded and reflected. The columella is 

 excavated and spreads over the base as a whitish callus. 



The specimen described and figured (U.S.N.M. no. 313617), col- 

 lected by Quadras on Mindoro, has 5.2 whorls and measures: Length, 

 29.9 mm; greater diameter, 26.3 mm; lesser diameter, 23.4 mm. 



A series of the specimens in our collection yields the following 

 measurements: 



