GOXIOBASIS. 309 



allied to Melanin inipoidca, Auth. It is more elongate and has only 

 three bauds usuall}-, which are deep brown, well defined and nearly 

 equidistant ; but sometimes has a thin additional one below the middle 

 one. Neither of the two specimens before me has a perfect apex, 

 so that the number of whorls might be determined, but a perfect 

 mature specimen would probably exhibit seven. In the penultimate 

 whorl are two bands ; on those above only one can be observed. The 

 aperture is more than one-third the length of the shell. — Lea. 



215. G. Showalterii, Lea. 



Melanin ShonviUerii, Lea, Proc. Acad. Xat. Sci., 18C1, p. 120. 



Goniobasis Showalterii, Lea, Jour. Acad. Nat. Sci., v, ot. 3, p. 220, t. 34, f. 4. Obs., 

 ix, p. 42. 



Description. — Shell smooth, raised conical, rather thick, yellowish- 

 brown, four bauds; spire obtusely elevated; sutures impressed; 

 whorls about six, flattened above, somewhat inflated below, the last 

 rather large; aperture rather large, ovately rhombic; whitish and 

 banded withiu ; outer lip sharp and slightly sinuate; columella white 

 inflected, slightly thickened above, rounded at the base. 



Operculum elongate, tongue-shaped, narrower at the outer end, 

 dark brown, without polar point, having parallel, transverse, slightly 

 curved striae. 



Habitat. — Coosa and Cahawba Rivers, Alabama; Dr. E. R. Showalter. 



Diameter, -42 •, length, of an inch. 



Observations. — This remarkable shell was sent to me by Dr. E. R. 

 Showalter last summer who called my attention to the very unusual 

 form of its horny operculum, which in the old specimens is half an inch 

 long, being a quarter of an inch wide at the inner end, gi-ad- Fig. 595. 

 ually diminishing to an angular point at the outer end. It 

 is usually curved, the outer end forming a half circle from 

 the base, the starting or inner end. Thus quite half the 

 length extends outside of the outer lip, the inner half 

 stretching across the aperture of the shell. Dr. Showalter 

 did not observe whether there was any difference in the soft parts 

 of this species from other Goniobases, but proposes to examine liviuj; 

 specimens. He remarks in his letters that "the operculum is very 

 striking and not observed in any other species, the mouth being 

 remarkably uniform in its shape, as indeed it is in its general form 

 and aspect." '-Some of the Coosa Anculosce," he says, "have this 



