HELIX-OBBA. 233 



H. REEVEANA Pfeiffer. PL 55, figs. 31, 32, 33, 34, 35, 36. 



Shell umbilicated, depressed, lens-shaped, obtusely keeled at the 

 circumference ; yellowish with three (3 to 5, according to Pfr.) 

 chestnut bands ; delicately obliquely striate, the base concentrically 

 striated. Aperture subhorizontal, its width not 1 times its length. 



A form closely allied to H. horizontalis, but having a less narrowed 

 mouth and concentric striae on the base. Whorls 4i, flattened, the 

 last abruptly deflexed in front, convex beneath. Behind the reflexed 

 peristome it is deeply constricted, having above a gibbous ridge be- 

 hind the constriction. Aperture nearly horizontal, elliptical ; per- 

 istome continuous, reflexed, its face thickened, upper margin flesh- 

 colored, basal lip white, having a very slight indication of a tooth in 

 the middle. Umbilicus one-tenth the diameter of the shell. 



Alt. 10, greater diam. 24, lesser 21 mill. ; alt. 12, greater diam. 

 30, lesser 24 mill. 



Island of Zebu, Philippines. 



H. Reeveana PFR. P. Z. S. 1846, p. 42 ; Monographia i, p. 377 ; 

 Bolster's Conchyl. Cab., t. 75, f. 6-8. Obbina reeveana MOLLEN- 

 DORFF, Bericht Senckenb. naturforsch. Ges. 1890, p. 220. 



A form closely allied to H. horizontalis, but without a brown area 

 in the middle of the base, having a less contracted mouth, and the 

 basal lip has no trace of a tooth at the position where it is 

 developed in H. horizontalis. Mollendorff has found a more cari- 

 nated form. 



H. LASALLII Eydoux. PL 54, figs. 20, 21, 22. 



Shell umbilicated, depressed, rather thick, smooth, tawny, three- 

 zoned with brown and marbled with whitish. Spire slightly con- 

 vex ; whorls 42-5, nearly flat, the last cylindrical, suddenly de- 

 flexed at the aperture. Umbilicus moderate. Aperture horizontal, 

 ear-shaped ; peristome much thickened, reflexed, continuous, the 

 upper margin sinuous, impressed, basal margin obsoletely toothed. 



Alt. 12, greater diam. 28, lesser 22 mill. (Ffr.~) 



Luzon, Philippines. 



H. lasallii EYDOUX, in Guer. Mag. de ZooL, t. 115, f. 1. PFR. 

 in Conchylien Cab., p. 62, t. 77, f. 4-6 ; Monographia i, p. 380. 

 REEVE, f. 121. IT. meretrix SOWB. P. Z. S. 1841, p. 20. PFR. 

 Symbolse, ii, p. 33. REEVE, Conch. Syst. ii, t. 163, f. 6. Obbina 

 Lasallii (Eyd.) MOLLENDORFF, in N. D. M. Ges. 1888, p. 87, with 

 forma subcarinata, f. subcostata, and varieties obscura and grandis. 



