186 OPEAS, POLYNESIA. 



Society Is. (HuaJiine) and Gambier I. or Mangareva in the 

 Paumotu group have a form similar to the Hawaiian pyrgiscus 

 in shape, but the columella is thickened by a low tooth-like 

 callus below (pi. 24, fig. 39, Mangareva). Half -grown shells 

 have the same columellar thickening. The specimen figured 

 is 10.8 mm. long. Those from the Society Is. are somewhat 

 smaller. A single specimen said to be from New Caledonia 

 is similar, but I am not certain of the locality. 



92. 0. HEPTAGYEUM Boettger. 



Differs from the allied species by the small peculiarly cyl- 

 indric shell of sufooqual whorls, the apex obtuse, suture very 

 deep. Shell small, perforate-rimate, subcylindric-subulate, 

 thin, silky, waxy-hyaline ; spire subulate, very slowly in- 

 creasing, the apex obtuse. Whorls 7, a little convex, flattep 

 below, separated by a very deep suture, distinctly but very 

 delicately striate, slowly increasing; the last whorl slightly 

 flattened in the middle, one-fourth the length of the shell. 

 Aperture small, oblong-oval; peristome simple, acute, the 

 right margin a little straightened, columellar margin very 

 narrowly reflexed; columella slightly arcuate, concave. 

 Length 6.12, diam. 2, alt. aperture 1.5, width 1 mm. (Bttg.). 



Marshall Is.: Nauru (Paul Schnee). 



Opeas heptagyrum BTTG., Zool. Jahrb., Abth. f. Syst., 

 Geogr. u. Biol. Thiere, xx, 1904, p. 411. 



"Seems to stand near 0. tuckeri Pfr. from Sir Charles 

 Hardy's Island, etc., but differs from the original diagnosis of 

 Pfeiffer by the decidedly obtuse apex, 7 instead of 9 whorls, 

 and by the index of width 1 :3,06, while 0. tuckeri has the in- 

 dex 1 :3,27, and must thus be narrower. Both are distin- 

 guished from other related species by the cylindric shape and 

 conspicuously short last whorl. (Bttg.). 



This is probably identical with 0. oparanum, or varietally 

 distinct by its smaller size. I have seen no Opeas from the 

 Marshall group. 



93. 0. OPELLA Pilsbry & Vanatta. PL 24, fig. 36. 



Shell cream-colored, glossy, indistinctly irregularly striate, 



