HELIX-OBBA. 215 



(Oxytes) Linnceana PFR., Nomencl. Hel, Viv. p. 54. TRYON:, Man. 

 ual, 2nd ser., vol. ii, p. 131, t. 43, f. 46. 



A magnificent species, looking like H. quoyi, if we imagine that 

 shell depressed and acutely keeled. It is very rare. The locality 

 above given is on the authority of Ancey. Sangir, or Great Sangi 

 (variously spelled) is a small island, lying south of Mindanao, of 

 about 30 by 10 miles extent, having a volcano in the center. Several 

 smaller islets are near it, connecting with Celebes. No other land 

 shells have been reported from them. 



Section OBBINA Semper, 1873. 



Gal Una HARTMANN, Erd und Siisswasser Gasteropoden, p. 197, 

 1840 (Helix rota Sowb.) Obba (part) BECK. Philina ALBERS, 

 Die Heliceen, p. 119 (preoc.). Obbina SEMPER, Reisen im Archip. 

 Phil., Landmoll. ii, p. 123 (type H. planulata), 1873. 



Shell variable in degree of depression (trochoidal to discoidal), 

 having a tendency to be carinated ; umbilicated ; nucleus composed 

 of about two polished whorls ; last whorl suddenly deflexed in front. 

 Aperture very oblique or horizontal ; peristome expanded, basal lip 

 reflexed, its terminations joined by a cord of callus. 



Nearly all of the species inhabit the Philippine Is. and northern 

 Celebes. 



Of the names given above, Gallina was not defined. Pusiodon 

 is a combination of Planispira and Obbina, a species of the former 

 leading. Philina is preoccupied. We are therefore justified, in 

 using Semper's thoroughly-defined name Obbina. 



The species have been grouped by some authors according to the 

 degree of carination ; others have considered the tooth of the basal 

 lip of more importance. Both these characters are too inconstant 

 to be of much use. Color-pattern and sculpture are far more 

 reliable characters. 



The species fall into four pretty well-defined groups as follows: 



(1.) Group of H. listeri. Roughly sculptured forms, generally 

 with one dark band above and one below, the aperture dark inside. 

 Basal lip toothed, the tooth often obsolete. 



(2.) Group of H. moricandi. Having a strong tooth on the basal 

 lip marked by a pit behind the peristome. Aperture light inside ; 

 base microscopically spirally striated. 



(3.) Group of H. marginata. Basal lip without any trace of a 

 tooth. Shell banded but not obliquely streaked or speckled, rather 

 thin. 



