164 THALESSA. 



P. MELONES, Duclos. PI. 47, fig. 56. 



Dark chestnut, variegated with white, especially upon the 

 periphery and inferior portion of the bod}^ ; columella tinged 

 with pink ; outer lip frequently black-bordered. 



Length, 1*5-2 inches. 



Pacific Coast of Central America. 



The want of nodules or spines disagrees with the character of 

 the group ; yet the relationship of this species with P. deltoidea 

 is tolerably close. Sometimes the body-whorl is, in adults, con- 

 stricted around the middle. Morch describes the animal in 

 Mai. Blatt., vii, 99. 



P. TRIANGULARIS, Blainv. PL 47, fig. 57. 



White ; more or less stained with light brown externally. 



Length. 1 inch. 



Mazatlan to Panama. 



Something like P. triserialis, but differs in the equal develop- 

 ment of the second row of revolving tubercles. 



P. MANCINELLA, Linn. PL 47, figs. 59-61, 63, 64. 



Shell 3>ellowish, the tubercles frequently tinged with red ; aper- 

 ture varying from white (P. echinata ) to deep yellow ; in the latter 

 with the raised interior revolving lines darker colored (typical). 

 Length, 1*5-2*5 inches. 



Bay of Muscat; Singapore; Fiji Isles; W. Coast Central 



America ; Peru ; Japan ; Australia. 



The more elevated and more sharply tubercled forms, white 

 without and within, are called P. echinata (fig. 63). and might 

 continue to be so designated as a variety, but the intermediate 

 gradations are very complete. P. segrota, Reeve (fig. 64), said 

 to inhabit the waters of Japan and Australia, is one of these 

 intermediate forms. 



P. LUTEOMABGINATA. Montrouzier. PL 47, fig. 62. 



Yellowish white, the nodules chocolate ; margin of lip and 

 columella tinged with orange. Length, 1*6 inches. 



New Caledonia. 



This may be a mere variety of the preceding species, but has 

 relationships with P. bimaculata also. 



