146 AMPHIDUOMUS, GROUP IV. 



This species differs from A. perversus in the larger aperture, which 

 is more oblique and more acuminate above, in the recurved but not 

 smoothly adnate lip, and in the deep color of the inner layer of the 

 shell (whence the name entobaptus, dyed within), which however 

 does not hold in white examples. Dark varices are never developed. 

 Dohrn writes as follows : "In this species the yellow layer of the 

 shell is on the inside, but in A. perversus it is external ; and there- 

 fore the inside of the aperture in A. entobaptus is much more deeply 

 colored than the outside, which is covered by an uncolored layer, 

 while in A. perversus the inside is always pure white. The peri- 

 stome of entobaptus is white, the intensely citron-yellow or egg- 

 yellow being suddenly cut off. A section of the shell shows that 

 the colored layer is not quite so thick as the over.lying white layer, 

 and becomes thinner near the aperture, and in the formation of the 

 lip it gives place to the outer layer. In A. perversus the outer, 

 colored layer is thinner than the underlying alabaster-white layer." 



The coloration varies more than Dohrn was aware of, the chief 

 forms before me being as follows : 



(1) Shell stout, decidedly conic, alt. 42^, diam. 25, aperture 24 

 mill, (a) Colored as in (rf), but with a narrow white subsutural 

 band, or flesh-tinted, yellow inside (fig. 44). (b} Pale lemon or 

 greenish-yellow, or fleshy-yellow, as though overlaid with n thin 

 white layer, or almost white, the interior deep yellow, fig. 43. (c) 

 Pure white throughout, fig. 42. 



(2) Shell ^vnder, alt. 47, diam. 24, aperture 24 mill, (d) 

 Bright straw-yellow outside and within, the white sutural line 

 scarcely noticeable, fig. 46. (e) Very pale citron, somewhat deeper 

 inside, fig. 45. Paragua. 



The varieties grouped above under (1) seem to be typical ento- 

 baptus, although the specimens figured and others before me are 

 from Busuanga. Those grouped under (2) may be von Moellendorff's 

 gracilis, but the specimens figured were received from him some 

 years ago as from Paragua. I know nothing of the undescribed 

 variety contracta Mlldff. Hidalgo, in his magnificent iconography 

 of the Philippine fauna, has figured yellow, reddish, violaceous and 

 green color-forms. 



As Puerto Princesa is near the southwestern end of Palawan, the 

 species probably occurs throughout tke length of that island, and 

 through the Calamianes to Busuanga. In the other direction if 



