OF CONCHOLOGY. 303 



PLEUROCERA, Raflnesque. 

 a. Tuherculate. 



1. P. alveare, Conr. Figs. 1 — 7. Short, conical, ventri- 

 cose, wliorls flattened, tuberculate on the periphery, base 

 scarcely convex, concentrically striate ; aperture sub-rhom- 

 boidal. Horn-color. Tenn., North Ala. 



Figs. 1, 2, 3, 4 are typical, 4 is also pernodosa, Lea. Figs. 5, 6 are tor- 

 quata, Lea, a larger variety, and Fig. 7 is grossa, Anth. , the quite young 

 shell of the large variety. 



2. P. Foremanii, Lea. Fig. 8. Pyramidal, thick, ele- 

 vated ; whorls 9, flattened, the last convex ; periphery tuber- 

 culate, in one or more rows, not angulate ; aperture long, an- 

 gular. Yellowish-brown, white within. lY. Ala. 



2a. P. Lesleyi, Lea. Fig. 9. Obtusely conical, pyramidal, 

 tuberculate; spire elevated, with irregularly impressed suture; 

 whorls 8, the initial ones plicate when perfect, the others sili- 

 cate and carinate, the carina tuberculate ; aperture small, 

 rhomboidal. Dark corneous, sometimes banded. Pulaski 

 Co., Ky.; E. Tenn. 

 Differs from the following in the broad conical form and plicate spire. 



3. P. undulatum, Say. Figs. 10, 11. Pyramidal, ele- 

 vated; spire acute; whorls 8 — 9, flattened, with a broad cen- 

 tral sulcation, below which is a carina, elevated at times into 

 transverse raised tubercles; aperture oblique, rhomboidal. 

 Brown to green, sometimes banded with brownish-red. Ohio 

 River and all its trihitaries. 



4. P. excuratum, Conr. Figs. 12 — 15. Pyramidal, sub- 

 ulate; whorls 10 — 12, flattened, the periphery ornamented with 

 close, small, oblique tubercles upon the angle; above, the body 

 whorl is slightly excavated above the periphery, below it is 

 striate; first few whorls closely striate when not eroded. Brown. 

 Tennessee River, Florence, Ala. 



Differs from undulatum in its narrower, more elongated form, and in 

 the striate initial whorls. The next to last figure is P. Spillmanii, Lea. 



5. P. moniliferum, Xea. Figs. 16 — 18. Pyramidal; spire 

 elongated ; suture irregularly impressed ; whorls 10, flattened, 

 sometimes obscurely sulcate, angulate and tuberculate on the 

 periphery, striate below; aperture rather large, rhomboidal, 

 outer lip acute, very sinuous, at base very much twisted. Yel- 

 lowish or greenish, generally two-banded, white or salmon- 

 color within. Lower Ohio River, Ky., throughout Tenn., North 

 Ala. 



Narrower and more elongated than undulatum, upper whorls not striate 

 like excuratam, also distinguished from the latter by being two-banded. 

 The 2d figure is nodosa. Lea, the 3d variabilis, Lea. 



