HELIX-OBBA. 225 



in H. scrobiculata, its edge but little elevated, whilst in the rota this 

 margin is usually decidedly elevated. 



H. ROTA Broderip. PL 56, figs. 77, 78, 79. 



Shell umbilicated, depressed, lens-shaped, acutely carinated, light 

 brownish, occasionally with oblique white streaks, having three nar- 

 row brown bauds above, two beneath. Surface sculptured by prom- 

 inent elevated, thread-like oblique riblets, arched in the direction 

 of growth-lines ; the base having also microscopic close spiral lines. 

 Basal lip toothed in the middle. Carina fluted. 



Shell about as convex above as below, or else nearly flat above. 

 Whorls 4J, the inner two whitish, smooth ; last whorl abruptly de- 

 scending, constricted behind the basal lip, with a slight pit there, 

 marking the position of the lip tooth. Aperture horizontal, ellip- 

 tical, white and showing the bands within. Peristome white, con- 

 tinuous, expanded, basal lip reflexed, strongly toothed in the mid- 

 dle. The outer bands of the body-whorl are on the carina. 



Alt. 10, greater diam. 29, lesser 24 mill. 



Alt. 8, greater diam. 23, lesser 19 mill. 



Visayas Is., Philippine group (Hidalgo) ; Siquijor (Cuming) ; 

 north coast of Bohol; Lampinigan, near Basilan ; Balatanai an islet 

 near Lampinigan; Islas Camotes, north of Bohol (Semper). 



Helix rota BROD. P. Z. S. 1841, p. 45. PFR. Monographia, i, p. 

 403 ; Conchyl. Cab. p. 68, t. 78, f. 16-18. REEVE, Conch. Icon. f. 

 128. HIDALGO, Journ. de Conchyl. 1887, p. 104. Carocolla rota 

 REEVE, Conch. Syst. ii, t. 167, f. 1, 4. Gallina rota HARTM. Gast. 

 Schw., p. 197, t. 76. Lucerna rota ADS. Obbina rota SEMPER, 

 Reis. Arch. Phil. Landmoll., p. 122. MOLLENDORFF, Bericht 

 Senckenb. Naturf. Ges. 1890, p. 220. 



This species has strongly elevated, thread-like oblique riblets, and 

 and a wavy or fluted keel. The riblets are nearly obsolete on the 

 base in some specimens ; the localities given for these are S. Juan de 

 Surigao. on the eastern coast of Mindanao, Limansaua, west of 

 Surigao, Islas Camotes, Tubigon, east coast of Bohol, and Mac- 

 Crohon, south coast of Leyte. Another variety with rugose but not 

 ribbed base, feebly crenate or smooth carina, is found at Malitboc, 

 south coast of Leyte, Limansaua, Mac-Crohon, Leyte and Islas Cam- 

 otes, northward of Bohol. This last variation is much like H. scrob- 

 iculata, but differs in the arrangement of the bands. A third variety 

 was found by Semper at Maribojoc, west coast of Bohol. It is very 

 15 



