THK NAUTILUS. 135 



n lly anastomosing or splitting. Whorls 4^, convex, tubular, rapidly 

 enlarging, the last becoming almost free from the preceding near its 

 termination. Aperture but slightly oblique, subcircular, a little 

 angular above. Peristome obtuse, continuous, a trifle excised and 

 retracted on the parietal margin. Umbilicus ample, showing all the 

 whorls, its width contained 4^ times in that of the shell. Alt. 20, 

 diam. 31.5 mm. Length of aperture with peristome 14.5, width 

 14.3 mm. 



Operculum solid, perfectly flat, dull and white externally, com- 

 posed of about 7 whorls, which are raised in a low ridge or welt on 

 the inner edge, and very obliquely striated, the nucleus a little 

 sunken, and not raised inside. Diam. 12 mm. 



Las Nubes estate, Santa Marta Mts., Colombia, at 4000 ft. elev. 

 A single specimen. 



Related to A. popayanum, but the umbilicus is wider, the strife 

 stronger, and with another color-pattern. A close examination 

 shows some very faint traces of spiral bands. 



Aperostoma smithi n. sp. PI. vii, figs. 5, 8. 



Shell rather narrowly, deeply umbilicate, low-turbinate, very dark 

 chestnut with indistinct wide, black streaks, the eroded inner whorls 

 dull red ; moderately solid. Surface glossy, with sculpture of close 

 rib-stria?, which are a little, waved or crimped. Whorls fully 4, con- 

 vex, rapidly widening. Aperture large, moderately oblique, circular, 

 a trifle angular above. Peristome blunt, continuous, in contact with 

 the preceding whorl for a short distance only. Umbilicus deep, its 

 diameter contained 9 or 10 times in that of the shell. 



Alt. 14, diam. 20 mm.; length of aperture 10.5, width 10 mm. 



Alt. 14.5, diam. 19.5 mm.; length of aperture 10.8, width 10 mm. 

 Operculum whitish externally, composed of about 6 flat whorls 

 around a sunken, corneous nucleus about 1 mm. diam. Internally 

 there is a slight central mucro, which lies just within the edge of the 

 dull scar of attachment. Diam. 9 mm. 



Santa Marta Mts. at El Libano, at 6500 ft. elevation, under de- 

 caying leaves in forest. 



It is about the size of A. dysoni, but with stronger, straighter rib- 

 striae and slightly more oblique aperture. A. pazi Crosse is some- 

 what similar, but has a wider umbilicus, smaller aperture and is more 

 depressed. A. smithi has a much smaller umbilicus than A. sancta 



