PLEUROCERA. 79 



This shell is veiy nearly allied to P. iwnderosum^ Anthony 

 (P. dux. Lea). The figure is from Mr. Lea's plate but differs 

 in the form of the aperture, in color and in size. 



22a. P. canalitium, Lea. 



Trypiiiostoma cannlitinm, Lea, Proc. Acad. Nat. Sci., p. 175, 18fi2, Jour. Acad- 

 Nat. Sci., V, \)t. 3, p. 292, t. 36, f. 121. Obs., ix, p. 114. 



Description. — Shell canaliculate, conical, rather thick, horn-color, 

 obscurely banded; spire regularly conical, some\Yhat raised, double- 

 banded towards the point; sutures impressed; whorls about Fi?. us. 

 seven, flattened, the last canaliculate ; aperture small, rhom- 

 boidal, white or salmon, and banded within ; outer lip sharp 

 and sigmoid ; columella twisted, recurved at the base. 



Habitat. — Yeilowleaf Creek, Alabama; E. II. Showalter, 

 M.D. 



Diameter, -43; length, -99 of an inch. 



Observations. — Three specimens are before me all of the same size, 

 and having the appearance of half-grown Melania {Trijpanostoma) 

 canaliculata, Say, but they are mature and evidently distinct. Tiie 

 channel above the middle of the whorl is smaller, but well character- 

 ized. In the form of the aperture they are very much the same, being 

 auger-shaped like Cerithiurn. It is very nearly allied to Melania 

 {Trypanostoma) infrafasciata, Auth., from Tennessee, but may be 

 distinguished by its channel above the middle of the whorls, and in 

 having three bauds visible in the interior, while the infrafasciata 

 has but one, as described by Mr. xVnthony, and none on the superior 

 whorls, as all our three have. The aperture is about three-tenths the 

 length of the shell. — Lea. 



This figure is a copy of Mr. Lea's. In specimens of this 

 shell, from Columbus, Miss., tlie canal is much better developed 

 than in the above figure. 



23. P. Clarkii, Lea. 



Trypanostoma Clirhii. Lea. Proc. Acad. Xat. Sci.. p. 171, 18G2. Jour. Acad. Nat. 

 Sci., V, i)t. 3, p. 285, t. 3i;, f. 108. Obs. i.\, p. 107. 



Description. — Shell obtusely carinatc, conical, rather thick, dark 

 olive ; spiro raised ; sutures very much impressed ; whorls about 



