228 



LAND AND FRESH-WATER SHELLS OF N. A. [PART L 



straight, numerous, 7-18 in number, gradually enlarging; 

 apex obtuse; aperture semi-oval or ovate-oblong; 



Fig- «388. peristome straight, generally simple ; columella 



^d^^^ usually truncated. 



Jaw of stmo- Jaw arcuatc, delicately striated and denticulate. 



^[Moq.-tLjd.] Middle lingual teeth very small. 



Spbgenus RUMINA, Risso. 



Shell obsoletely rimate, calcareous, normally truncated, cylin- 

 drically-elongate ; remaining whirls 4-6, the upper truncated 

 ones 8-1 0, the upper one globular ; aperture semioval ; peristome 



straight, thickened within, its 

 margins connected with callus, 

 the columellar twice as short as 

 the external one; columella not 

 truncated. 



Animal short, stout, surface 

 finely granulated ; tail short, rather bluntly terminating ; eye- 

 peduncles long, slender, tentacles very short. 



Fig. 389. 



Animal of Stenogyia decollata. 



Fis. 390. 



Stenogyra decoBlata, Linn. — Shell rather thick, long, cylindrical, 

 turreted ; epidermis shining, whitish, with a slight tint of brownish or 

 yellowish; apex obtuse; spire gradually enlarging .from the apex to the 

 aperture, commonly abruptly truncated betweeif the third and 

 fifth whirls next the aperture ; whirls remaining three to five, 

 flat, a little wrinkled, and in the last two or three slightly 

 crenate, or plaited below the suture ; suture not impressed ; 

 aperture lateral, oval, angulated superiorly, its plane very 

 nearly parallel with the axis of the shell ; peristome simple, 

 thickened within, its columellar portion reflected. Axis of the 

 truncated shell usually about 25 mill., diameter of the largest 

 whirl less than 12 mill. 



Helix decollata, Linn^tts, Syst. Nat. 1247, &c. 

 Bulimus decoUatus, Draparnaud, 76, pi. iv, f. 27, &c. — 

 Pfeiffer, Mon. Hel. Viv. IV, 456.— Binney, Terr. Moll. 

 II, 280, pi. 1, f. 1.— W. G. BiNNEY, Terr. Moll. IV, 131.— Leidy, 

 T. M. U. S. I, 259, pi. XV, f. 5, 6 (1851), anat. 

 Bulimus multilatus, Say, Journ. Acad. Nat. Sci. Philad. II, 373; ed. 

 Bisney, 25 (err. typ. for mutilutus'). 



