26 



B. emeus. With crowded, minute, transverse striae. 



Inhabits Mexico. 



Shell conic or elongate ovate, slightly angulated on the 

 middle of the volutions, and covered with minute, undulated, 

 impressed, capillary lines; whitish with maculated bands: su- 

 ture not deeply impressed: aperture much shorter than the spire: 

 labrum exteriorly simple, interiorly with a thickened submargin: 

 columella short, recurved: umbilicus small, but distinct: spire 

 with the angulation concealed by the suture: body whorl with 

 the angulation almost obsolete. 



Length, thirteen-twentieths of an inch: greatest breadth. 

 (parallel to the suture) three-tenths. 



I found this species on the road between Vera Cruz and 

 Mexico. As I possess only the "Tableaux Systematiques" of 

 Ferussac's splendid work, the preceding species of Bulimus 

 are offered with considerable hesitation ; but those who possess 

 lhat work, can readily detect an error if there be one. 



Note. — Bulla Puviatilis, .Nob., seems to be no other than the very deceptive 

 young of our common Planorbis. 



ANCYLUS. 



A. tardus. Shell conic-depressed: apex behind the middle, 

 obtuse, rounded, inclining backward but not laterally: line 

 from the apex to the posterior tip rectilinear; line from the 

 apex to the anterior tip arquated: aperture oval, not distinctly 

 narrowed at one end. 



Length, a little over three-twentieths 4-25; breadth, one- 

 tenth of an inch. 



Differs from A. rivularis, Nob., which has the apex leaning 

 towards one side and the aperture narrower at one end. It is 

 less elongated than Jluviatilis, Drap., which has an acute and 

 laterally inclined apex. 



It inhabits the Wabash River. 



