6 BOOK OF SPECIES. 
ash; margin dilated and acute. B.2...1}. W. 
37. 38. 
P. LEUCOPLEURA. Conical, ovate, smooth, 
light reddish ash rayed with irregular dark brown 
furcated lines ; summit white, obtuse, and girded 
with red; small. 
P. puncrurRATA. Oval, convexly tumid, 
white spotted with crimson; ribs flattish, radi- 
ating, and separated; inside white; muscular 
impression citron; summit blunt and sub-cen- 
tral; small. W. 38. 76. , 
P. pecTinATA. Oval, thin, obliquely conic, 
yellowish brown, with longitudinal striz, gar- 
nished with black imbricated rough scales; sum- 
mit inclined nearly to the margin; smallish ; not 
unlike genus Pileopsis. W. 37. 46. 
P. pELLUCIDA. Smooth, thin, pellucid, ob- 
ovate, gibbous, olive, with blue interrupted rays ; 
summit inclined to the margin. B. small. W. 
37. 58. 
P. monopis. Ovate - flattish, with about 
eleven large ribs, and intermediate smaller ones ; 
brown; when perfect, rayed with minute blue 
spots, but the outside is generally eroded; the 
