246 SOUTH AMERICAN OBELISCUS. 



phase of this species. His original figure, copied in my fig. 

 44, shows the pale color and angular periphery of youth. In 

 his second publication he mentions receiving others, up to 

 11 cm. long. In fig. 45 a young shell 71 x 15 mm., with 14% 

 whorls is drawn. The embryonic second whorl is 3.2 mm. 

 diam. The fully adult shell of this form is shown in fig. 47, 

 105 x 25 mm., with 11% whorls remaining. The shell is thin, 

 light, and pale greenish or grayish-buff in the young, but the 

 adult is solid, heavy, and of a rich chestnut-tinged olive- 

 yellow 'color on the later whorls, the earlier always whitish. 

 The surface is finely, sharply >and densely striate, the strias 

 interrupted by a few spiral lines in the immature stage, but 

 on the later whorls of the adult form this sculpture is more 

 or less obsolete. The apex is truncate in full-grown shells. 

 The columella is straight above, concave below, with no cal- 

 lous, but its edge is reflexed and closely appressed. 



There is a wider phase or form of this species in which the 

 spire tapers more rapidly and the whorls are shorter, a 

 greater number therefore being present in specimens of the 

 same length ; the other characters remaining practically iden- 

 tical. An adult 104 mm. long is 25% mm. wide, retaining 

 13 whorls. The immature and adult stages of this wider 

 phase are figured, pi. 34, figs. 46, 51. 



Specimens kept in captivity by Moricand brought forth 

 young ones. They are born in a capsule of clear, limpid 

 fluid confined by an extremely thin membrane, pi. 34, fig. 48. 



This species is type of the genus Obeliscus. The embry- 

 onic shell, pi. 37, fig. 100, taken from the shell drawn in pi. 

 34, fig. 47, is oblong, perforate, and composed of 3% whorls. 



2. 0. CARPHODES (Pfeiffer). PI. 34, fig. 53. 



Shell imperf orate, long-turrite, the apex obtuse, regularly 

 and closely striate, ashy-buff. Whorls 16 to 18, slowly in- 

 creasing, a little convex, the last nearly smooth, about two- 

 elevenths the length. Columella straight, simple, the aper- 

 ture oval, peristome unexpanded, acute, the columellar mar- 

 gin narrowly ivllrxrd, .-impressed. Length 72, diam. 14, aper- 

 ture 13 x 7 HUD. < /'/>.). 



