The Genus Gyrotoma ii 



produced at the base and has a node at the fissure. It attains full develop- 

 ment earlier in this species than in any other of the genus. The outer lip 

 is sinuous. The largest pyramidatum measured, which probably would have 

 eight whorls if uneroded, is 21 x ii 1-2 mm. 



A young: specimen from Lock. 2, having five whorls, is conic, carinated 

 at the periphery of the whorls, sharply angulate of base. The whorls are 

 flat and without folds. The columella is undeveloped. There is scarcely 

 more than an indication of fissure. Bands are three in number. 



!^Ir. Smith's lowest locality for pyramidatum is Hall's Island, Talladega 

 County. There are two specimens in the Schowalter Collection which I 

 judge to be this species. The locality is mouth of Yellowleaf Creek (Shelby 

 County). This is a few miles below Hall's Island. 



Dr. Walker compared specimens taken by Mr. Smith with types of 

 pyramidatum and conica in Geneva and found them to be the same. Conica 

 does not appear to have been formally described. Dr. Walker, who came 

 upon material in the Geneva Museum so labeled, suggests that the re- 

 marks at the end of the description of pyramidatum might have been in- 

 tended to refer to this form. 



Gyrotoma spillmatiii (Lea) 

 PI. I, figs. 4 and 5 



tSchizostoma SpUlmanii Lea, Proc. Acad. Nat. Sci., Phila., XIII, 1861, p. 54; Journ. 

 Acad. Nat. Sci., Phila., V, n. s., 1862, p. 250, pi. 35, fig. 55; Obs. Gen. Unio, IX, p. 

 7-, pl- 35, fig. 55- 



Schizostoma bahylonicum Lea, Tryon, Monog. Strepom., 1873, p. 369. 



Gyrotoma SpUlmanii Lea, Paetel, Cat., 1888, p. 2>'^2. 



Gyrotoma laeta inclsa (Lea), Hannibal, Proc. Malacol. Soc, X, 1912, p. 182. 



Schizostoma Wheatleyi Lea, Proc. Acad. Nat. Sci., Phila., XX, 1868, p. 153; Journ. 

 Acad. Nat. Sci., Phila., VI, 1868, p. 342, pl. 54. fig. 27 ; Obs. Gen. Unio, XII, 1868, p. 

 342, pl. 54. fig- 27; Lewis, Amer. Journ. Conchol., V, 1869-70, p. 169; Lewis, Fauna 

 of Ala., 1876, p. 23. 



Description: Shell striate, subcylindrical, rather thick, yellowish-brown, imper- 

 forate; spire obtuse, conoidal ; sutures impressed; whorls six, very much banded, flat- 

 tened, the last large ; fissure oblique and rather short ; aperture large, ovate and 

 Tjanded within, obtusely angular at the base ; columella white, thickened above ; outer 

 lip sharp and sinuous. 



Operculum ovate, spiral, rather large, dark brown with the polar point near to 

 the left edge, about one-fifth above the basal margin. 



Habitat : Coosa River, Alabama ; Dr. F. R. Showalter. 



Diameter, .48; length, .92 of an inch. — Lea. 



The fissure of spillmanii is like that of pyramidatum from Hall's Island. 

 The young, though larger, whorl for whorl, are hardly to be separated from 

 juvenile pyramidatum. The types carry the resemblance because they have 

 unusually shallow fissures for adult spillmanii. But this species in general is 

 a larger, coarser race, more boldly sculptured, pyramidal only in the adoles- 

 cent stage and so stepped at the suture as to suggest to Tryon that it was 

 the same as bahylonicum Lea. I think it can stand as a species, related 

 closely to pyramidatum or springing at no great distance in time from the 

 same ancestral form. 



