LAKD AND FRESn-WATER SHELLS OF N. A. [PART IV. 



specimens, the longest is one inch and six-tenths. It is nearly allied 

 to Melania {Trypanostoma) elonrjata (nobis), but is not cariuate 

 Fiff 146 ^^^^ ^^^^ species, nor are the whorls so flat. The two 

 specimens from Florence are larger, and very dark 

 brown. Of the six from Tuscumbia, four are yellowish, 

 and two are banded and greenish. Two of the yellowish 

 ones are disposed to salmon-color inside. There is a 

 slight disposition above the periphery to flatness or in- 

 dentation. The aperture is more than the fourth of the 

 length of the shell. — Lea. 



I have seen some specimens from Coosa River, 

 Alabama, in wliich the whorls are more convex than 

 Mr. Lea's figure. The species has a more extended 

 distribution than the above localities would indicate, Mr. Lea 

 having specimens from New Harmony, Indiana. 



The preceding species {Alabamense) may prove to be the 

 young of this shell. 



22. P. olivaceum, Lea. 



Trypanostoma olivaceum. Lea, Proc. Acad Nat. Sci., p. 172, 18G3. Jour. Acad. Nat. 

 Sci., V, pt. 3, p. 2: 0, t. ■^':, f. 117. Obs. ix, p. 11-2. 



Description. — Shell carinatc, subfusiform, rather thick, olivaceous; 

 spire rather obtuse ; sutures impressed ; whorls about eight, flatttened ; 

 aperture rath(.'r large, rhomboidal, whitish within; outer pj„ j^- 

 lip sharp, sinuous; columella thickened below and very 

 much twisted. 



Operculum ovate, dark brown, with polar point near to 

 the base. 



Habitat. — Tombigbee Kiver, Mississippi; W. Spillman, 

 M. D. 



Diameter, -50; length, lOG inches. 



Observations.— Dr. Spillman sent me quite a number of this species. 

 In outline and size it is very near to Strephobasis olivaria (nobis), but it 

 (jiffers in the base of the columella, which separates it from the genus 

 Strephobasis, and it is more flattened on the whorls, and is not banded ; 

 except in rare cases it lias an obscure small band near the base. The 

 olive-green hue of the epidermis is very constant. The carina gener- 

 ally leaves a thread like line along the suture. The aperture is about 

 one-third the length of the shell.— Lea. 



