486 



BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



COCHLOSTYLA (CHRYSALLIS) PALLIOBASIS Bartsch 



Plate 110, Figure 3 



1932. Cochlostyla (Chrysallis) palliobasis Bartsch, Journ. Washington Acad. Sci.,. 

 vol. 22, p. 340. (June.) 



1932. Helicostyla mcgintyi Smith, Nautilus, vol. 46, p. 63, pi. 4, figs. 1, 2. (Oct.) 



1933. Helicostyla (Chrysallis) mindoroensis orolis Clench and Archer, Papers 



Michigan Acad. Sci., Arts, Letters, vol. 17, p. 549, pi. 58, fig. 1. 



Shell pupoid. The nuclear whorls are pale buff. The early post- 

 nuclear whorls are very pale brown, gradually deepening to light 

 chestnut-brown on the last turn. This coloration stops abruptly at 

 the periphery, and the base is buff shading gradually toward brown 

 on the last half of the last turn. In addition to this ground color, 

 the postnuclear whorls are fulgurated with rather broad hydrophanous 

 olivaceous-buff axial markings. The anterior portion of the shell sur- 

 rounding the umbilicus and the columella is blackish chestnut-brown. 

 The interior of the aperture is bluish white, deepening on the outer lip 

 and columella to decidedly bluish. Both the outer lip and the colu- 

 mella are edged with dark brown. The parietal wall is glazed with 

 a thin translucent callus. Nuclear whorls 2.9, forming a moderately 

 acute apex, well rounded, smooth, marked by retractively curved 

 lines of growth and the last one by fine spiral striations. The post- 

 nuclear whorls are slightly rounded, appressed at the summit, and 

 marked by retractively slanting lines of growth and fine, closely 

 spaced, microscopic spiral striations, which are present on both spire 

 and base. Aperture broadly oval; peristome broadly expanded and 

 reflected. The columella is also broadly expanded at its insertion 

 and reflected to form the narrow umbilicus. 



This species is most conspicuously distinguished from all the others 

 by having the basal half pale buff as contrasted with the chestnut 

 coloration of the upper portion of the last whorl. 



The type (U.S.N.M. no. 313653) collected by Pedro de Mesa at 

 Pinagabyan, Paluan, Mindoro, has 7.2 whorls and measures: Length, 

 61.7 mm; greater diameter, 27.7 mm; lesser diameter, 22.5 mm. 



Four topotypes, also collected by Mr. de Mesa, entered as U.S.N.M. 

 no. 313656, yield the following data: 



1 Average. 



3 Greatest. 



'Least. 



