212 TERTIARY PERIOD. 



Subclass DICECA. 

 Order PECTINIBEANCIIIATA. 



Suborder T^NIOGLOSSA. 



Family MELANIID^. 



Genus GONIOBASIS Lea, 1862. 

 Goiiiobasis tenuicarinata Meek and Haydeu. 

 Plato XXI, iig. 10 a and b. 

 Melania tenuicarinata Meek and Hayden, 1857, Proc. Acad. Nat. Sci. Phila., 136. 



Shell conical, turreted, moderately elongate ; apex someAvhat acute ; 

 volutions six or seven, convex, but the upper portion of the outer side is a 

 little flattened obliquely ; suture deeply imj)ressed ; aperture ovoid, obtusely 

 angular at the posterior part, where the outer lip joins the inner one ; 

 outer lip sinuous, somewhat prominent below the middle ; coliimella slightly 

 curved; surface marked by the usual regular lines of growth, and also 

 along the middle of the volutions by elevated revolving lines, which vary 

 in number and distinctness in different shells, but in all they are obsolete 

 near the apex. The upper one of these lines is constantly more prominent 

 than any of the others, its prominence sometimes being sufficient to give a 

 somewhat tabulated appearance to the upper part of the whorls ; the next 

 most prominent line is a little below the one just mentioned, and in some 

 shells these two only are to be distinctly seen ; in other shells the whole 

 surface below these two is marked by other similar but a little less distinct 

 revolving lines. 



Length of the largest example in the collection, sixteen millimeters ; 

 breadth of body-whorl of the same, nearly eight millimeters. 



Position and locality. — Strata of Tertiary age ; Wales, Utah. 



Goniobasis tenera Hall, sp. 

 Plate XXI, fig. 11 a, T>, and c. 

 Cerithium tenerum Hall, 1845, Expl. Exp. Oregon and Northern California, 308. 



Shell turreted, very slender ; volutions about twelve, moderately con- 

 vex, longitudinally jilicate ; suture impressed ; aperture suboval, considera- 

 bly extended forward ; columella curved ; outer lip thin. 



