THALESSA. 1 6f 



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 



oolumella. 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, figs. fir>. <>7, 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, onl}- 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 striae ; 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 



