THALESSA. 166 



P. LISCHKEI, Kiister. PL 48, fig. 68. 



Light brown with four whitish subnodulous revolving ribs, 

 lineated with chestnut-brown ; aperture tinged with orange. 



Length, 1*6 inches. 



Habitat unknown. 



Has very much the appearance of a depauperate variety of P. 

 luteomarginata. If identical, P. Lischkei will have priority. 



P. BIMACULATA, Jonas. PI. 48, fig. 67. 



White, the rounded nodules black ; a black spot at the base of 

 the columella and a similar one at the base of the outer lip. 



Length, 2 inches. 



Zanzibar. 



P. NERITOIDEA, Linn. PL 48, figs. 72, 73, 69. 



Whitish, externally more or less penciled with brown revolv- 

 ing lines ; two or more round black spots on the middle of the 



columella. Length, 2 inches. 



Cape Verde Is.; Ascension Isl. 



The type is tuberculate, but the variety Ascensionis, Quoy 

 (figs. 69, 73), is smooth ; both have the characteristic black spots 

 on the columella. 



P. BUFO, Lam. PL 48, tigs. 66. 67, 71. 



Yellowish white with brown revolving lines ; interior of aper- 

 ture flesh-color, sometimes showing revolving brown lines like 

 the exterior. Substance of adults very thick, not banded within. 



Length, 1-5-2-5 inches. 



Philippines, on rocks at low water. 



Varies from nearly smooth, only some slight tubercles on the 

 shoulder, to forms having several revolving rows of tubercles. 



P. multilineata, Kiister (fig. 71), is the young of this species ; 

 I also figure a young shell with well-developed tubercles, from 

 Kiener (fig. 70). 



P. TRINITATENSIS, Guppy. 



Solid, ovate, yellowish, subrimate ; with numerous spiral ridges 

 crossed by fine imbricating stride ; four spiral rows of obtuse, 

 elongated tubercles, the superior one forming the angle of the 

 body -whorl ; mouth pink within, often with two or three more or 



