188 HELIX-SOL AROPSIS. 



The principal mutation to which this species is subject is in colora- 

 tion ; the red spots being sometimes almost completely obsolete 

 above ; a close inspection will reveal traces of them beneath the 

 suture, however. The peculiar surface sculpture described above 

 is very characteristic. There is a form which is almost always very 

 pale, even whitish in color, the tawny markings reduced or sub- 

 obsolete, the spire scarcely at all elevated. It may be called var. 

 PLANIOR. Figures 8-10, pi. 53, represent this form. This is not an 

 uncommon shell in collections. 



H. NAPENSIS Crosse. PL 51, figs. 87, 88, 89. 



Broadly umbilicate, depressed, planate, rather thin, above with 

 strong, rugose, submalleated, oblique, rather distant strise ; pale 

 fulvous, with two bands of alternating red and white spots, a wide 

 one below the^uture, and another above the periphery ; spire planate, 

 obtuse ; apex scarcely prominent ; suture deeply impressed ; whorls 

 5, nearly flat, the first 1? smooth, pale fulvous, the last scarcely 

 descending, acutely carinated, convex below, encircled by an obscure 

 series of reddish spots, obliquely roughly striate, obtusely subangular 

 around the umbilicus, and destitute of striae ; aperture oblique, ovate- 

 lunar, whitish inside ; peristome white, margins remote, the colu- 

 mellar subdilated, narrowly reflexed, somewhat attenuated out- 

 wardly. (Crosse.) Alt. 14, diam. maj. 32, min. 27 mill. 



Between Quito and Napo, Ecuador. 



H. napensis CROSSE, Journ. de Conchyl. 1871, p. 228, 414, t. 13, 

 f. 1. 



H. ROSARIUM Pfeiffer. PL 60, figs. 13-15 ; pi. 61, figs. 6-10. 



Umbilicate, depressed, thin, subtranslucent, light corneous brown, 

 with a series of short radiating chestnut-colored flammules under the 

 suture and three narrow bands of chestnut spots, one above, one 

 peripheral, one on the outer part of the base ; surface shining, 

 granulate above (under a lens), smoother beneath, and with a few 

 spiral impressed lines; spire only a trifle elevated, obtuse; sutures 

 well impressed ; whorls 4, convex, the last wide, gradually de- 

 scending ; aperture slightly oblique, broad lunar, whitish tinted with 

 lilac inside ; peristome very narrowly expanded, white, basal margin 

 slightly sinuous, superior margin somewhat flattened, sloping ; colu- 

 mellar margin a trifle dilated. Umbilicus deep, 2 mill. wide. 



Alt. 9, diam. maj. 19, min. 16? mill. 



Alt. 9, diam. maj. 21, min. 17 mill. 



Banks of the Amazon; New Grenada; Surinam* 



