THALESSA. lCr> 



P. LiscHKEi, Kiister, PI. 48, fig. 68. 



Light brown with four wiiitish 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 F. 

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



P. BIMACULATA, Jouas. 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, Limi. PI. 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. 



Vape Verde h.; Ascension Isl. 



The type is tuberculate, but the variety Ascensionis, Quoy 

 (fi:gs. 69, 73), is smooth ; both have the characteristic black spots 

 on the columella. 



P. BUFO, Lam. PI. 48, figs. 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, l'5-2-.^) inches. 



Philippines, on rocks at low water. 



Varies from uearl}- 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 (tig. 70). 



P. Trinitatensis, Guppy. 



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

 crossed by fine imbricating striai ; 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 



