PARTULA, MARIANNE ISLANDS. 317 



tumid in front. Columella short, shortly receding. Aper- 

 ture obliquely oval, glossy inside, yellow ; peristome simple, 

 thin, white, expanded, the right margin somewhat straight- 

 ened, columellar margin dilated above, spreading above the 

 umbilicus. Length 19, diam. 10, aperture 9x5 mm. inside 



(PA-.). 



Marianne Is.: Guam, on bushes (Cuming, Quadras, Rush). 



Bulnnus radiolatus PFR., P. Z. S. 1846, p. 39; Monogr. ii, 

 69. Partula radiolata PFR., Monogr. iii, p. 450; viii. 198; 

 Conchyl. Cab. p. 270, pi. 64, f. 17, 18. REEVE, Conch. Icon, 

 vi, pi. 2, f. 6. 



This form was at first supposed to be from New Ireland, 

 but was soon shown to come from Guam. It is a narrowly 

 iimbilicate, thin shell, copiously striped with corneous and 

 opaque white, with more or less suffusion of pale lemon yel- 

 low. In the more fully colored examples there are also many 

 olive-yellow lines among the stripes, scarcely visible except 

 under a lens. These lines dilate at the periphery, which 

 therefore, appears to have a faint band. This pattern is 

 shown in fig. 4. Other examples lack the dark lines and 

 peripheral band. The embryonic shell is very densely and 

 distinctly engraved spirally, the lines disappearing towards 

 the apex ; the first whorl is weakly plicate radially. The last 

 whorl is marked with rather widely spaced spiral lines, closer 

 on the base. In the typical form these lines are rather weak. 

 The last whorl is very full at the base. The lip is white, 

 narrowly reflexed, very little thickened within. Specimens 

 measure : 



Length 19, diam. 11.2, aperture 11 x 7.1 mm. ; whorls 



Length 17.5, diam. 11, aperture 10 x 7 mm. ; whorls 



Length 17, diam. 10, aperture 9.5 x 7 mm. ; whorls 4%. 



Length 16, diam. 9.9, aperture 10 x 7 mm. ; whorls 4%. 



A form (pi. 41, fig. 2) collected by Quadras is smaller, with 

 a brown band above the suture on the first 2y 2 or 3 whorls 

 of some specimens, the spire in others being -pale lemon tinted. 

 The last whorl has the typical coloration. The aperture is 

 more or less brown inside in those with a dark summit. The 

 first whorl does not seem to be plicate. 



