ODONTOSTOMUS. 41 



This group has evidently been derived from toothed forms with 

 similar apical sculpture, and in ray opinion has no real kinship with 

 the angle-based forms of Auri's, such as A., gomostoma, or with sim- 

 ilarly angular species of Drynuzus ; though the latter genus has the 

 same apical sculpture. The dark streak behind the lip, noticeable 

 in several of the species, is common to part of this group, and of 

 Bahiensis and typical Odontostonms ; and apparently was present in 

 their common ancestor, though now lost in some species of each of 

 these groups. 



Key to Species of Moricandia. t 



I. Length of aperture exceeding half that of the shell ; white, 

 uniform or with spiral bands ; basal spout long, bouvieri, p. 45. 

 II. Aperture less than half the length of the shell. 



a. Slender : length more than 3 times the diameter. 

 b. Aperture with a broad spout below. 



c. Smoothish, streaked; alt. 40, diam. 10-12 mill. 



dubiosus, p. 41. 



c. 1 Reticulate-malleate and finely striate spirally ; 

 30 x 9 mill., nasutus, p. 44. 



b. 1 Aperture angular below ; 29 x 9 mill., 



angulatuS) p. 42. 



a. 1 Length less than 3 times the diameter. 

 b. Suture not crenulate. 



c. Outer lip arcuate, angulatus, p. 42 \fidcznsis, p. 44. 



'c. 1 Both lips sinuous, auriscervina, p. 42. 



b. 1 Suture crenulate, brown-spotted; sharply striatulate 



and spirally striate, willi, p. 44. 



O. DUBIOSUS (Jay). PI. 9, figs. 1, 2. 



Shell deeply rimate, fusiform, slender and long, rather thin, 

 corneous, with narrow distant brown streaks and a purplish-black 

 stripe behind the white lip. Nearly smooth, the growth-lines fine 

 and inconspicuous. Spire very long, with slightly convex outlines, 

 apex obtuse. Whorls 9, slightly convex, the last tapering down- 

 ward, narrow and drawn out below. Aperture slightly oblique, 

 narrow, white with a blackish stripe within the lip; peristome white, 

 the outer lip but slightly expanded, strongly arcuate above, sinuous 



