182 HELIX-SOLAROPSIS. 



H. vipera PFR. in Proc. Zool. Soc. Lend. 1859, p. 27, t. 44, f. 6 ; 

 Malak. Blat. 1859, p. 29; Novit. Conch., ii, p. 149, t. 38, f. 12-14; 

 Monog. Hel. Viv., v, p. 373. 



Has a smaller aperture than the allied species. 



H. MONOLACCA Pfeiffer. PL 51, figs. 90, 91. 



Half-covered umbilicate, conoid-depressed, rather solid, striate and 

 granulate ; tawny, with close radiating reddish streaks, a trifle 

 undulating; spire conoid-convex ; apex obtuse 1 ; whorls 5^, a little 

 convex, sensibly widening, the last not descending, at the periphery 

 subangulated ; on the side opposite the aperture inflated above, and 

 markedly a lightly impressed scar or cicatrix ; base regularly ex- 

 cavated, indistinctly fasciate ; aperture diagonal, subtriangular- 

 lunar ; peristome white, margins joined by a thin shining callous, 

 the right one slightly expanded, basal thickened, reflexed, broadly 

 dilated over the umbilicus, nearly closing it. (Pfeiffer.) 



Alt. 21, diam. maj. 46, min. 39 mill. 



Surinam. 



H. monolacca PFR. in Malak. Blatter, iv, 1857, p. 155 ; Novit. 

 Conch., ii, p. 147, t. 38, f. 1, 2, 10, 11 ; Monographia Hel. Viv., iv, 

 p. 285. 



Described from a single example in Pfeiffer's collection. 



H. GIBBONI Pfeiffer. PL 51, figs. 84, 85, 86. 



Umbilicate, depressed, obtusely carinated, solid, light yellowish, 

 but so densely streaked and spotted with reddish-chestnut that the 

 ground-color is nearly covered except around the umbilicus. There 

 is a subsutural series of angular alternating reddish-chestnut and 

 whitish spots ; a narrower one above the yellowish periphery, and 

 several similar ones below it ; the base, inside of these, has numerous 

 concentric articulated lines and narrow bands, even into the 

 umbilicus ; the spaces between the bands are densely streaked and 

 clouded with reddish-chestnut, except around the umbilicus where 

 it is lighter. The surface is coarsely, obliquely striate above, less so 

 beneath, not granulate. The spire is convex, very obtuse, apex a 

 trifle sunken, apical two whorls unicolored, pale reddish, finely striate, 

 whorls 5, slightly convex, moderately, regularly widening, the last 

 obtusely angular at the periphery, convex beneath. Aperture broad- 

 lunar, oblique, bluish or lilac with a satin-like luster inside ; peri- 



