186 OPEAS, POLYNESIA. 



Society Is. (Huahine) 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. HEPTAGYRUM Boettger. 



Differs from the allied species by the small peculiarly cyl- 

 indric shell of suboqual 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, flatter- 

 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. O. OPELLA Pilsbry & Vanatta. PL 24, fig. 36. 



Shell cream-colored, glossy, indistinctly irregularly striate, 



