The Genus Gyrotoma 13 



Gyrotoma pagoda (Lea) 

 PI. I, figs. 6, 7, 8, and 9 



Schizostoma J>agoda Lea, Proc. Amer. Phil. Soc, IV, 1845, p. 167 ; Trans. Amer. 

 Phil. Soc, X, 1848, p. 93, pi. ix, fig. 52 ; Obs. Gen. Unio, IV, 1848, p. 93, pi. ix, fig. 52 ; 

 Journ. Acad. Nat. Sci., Phila., V, n. s., 1862, p. 247; Obs. Gen. Unio, IX, 1863, p. 69; 

 Lewis, Amer. Journ. Conchol., V, 1869-70, p. 169; Tryon, Monog. Strepom., 1873, 

 pp. XV, 365; Lewis, Fauna of Ala., 1876, p. 22,. 



Gyrotoma pagoda Lea, Chenu, Manuel, I, 1859, fig. 2,020 ; H. & A. Adams, Genera, 

 I, 1858, p. 305; Binney, Check List, i860, No. 327; Brot, List, 1862, p. 27; Paetel, Cat., 

 1888, p. z(>2. 



Melatoma pagoda Lea, Reeve, Monog. Melatoma, i860, sp. i. 



Schizostoma Wetumpkaetisis Lea, Proc. Acad. Nat. Sci., Phila., i860, p. 187; Journ. 

 Acad. Nat. Sci., Phila., V, n. s., 1862, p. 251, pi. 35, fig. 56; Obs. Gen. Unio, IX, 1863, 

 p. 73, pi. XXXV, fig. 56; Lewis, Amer. Journ. Conchol., V, 1869-70, p. 169; Tryon, 

 Monog. Strepom., 1873, p. 366; Lewis, Fauna of Ala., 1876, p. 23. 



Melatoma IVctumpkaoise Lea, Reeve, Monog. Melatoma, 1861, sp. 17. 



Melatoma ornata Anth., MSS., Reeve, ]\Ionog. Melatoma, 1861, sp. 11. 



Gyrotoma ornata Anth., Paetel, Cat.. 1888, p. 362. 



Melatoma Anthonyi Reeve, Monog. Melatoma, 1861, sp. 12. 



Gyrotoma Anthonyi Reeve, Brot. List, 1862, p. 27; Paetel, Cat., 1888, p. 361. 



Schizostoma Anthonyi Reeve, Lewis, Amer. Journ. Conchol., V, 1869-70. p. 168; 

 Tryon, Monog. Strepom., 1873, p. 368; Lewis, Fauna of Ala., 1876, p. 22. 



Melatoma funiculatiim Lea, Reeve, Monog. Melatoma, i860, sp. .S. 



Schizostoma pyramidatum Shutt., Hinkley, Nautilus, XVIII, 1904, p. 41. 



Gyrotoma lacta incisa (Lea), Hannibal, Proc. Malacol. Soc, X, 1912, p. 182. 



Description : Shell carinate, conical, rather thick, dark horn-color ; spire rather 

 short ; sutures very much impressed ; whorls si.K ; fissure small ; aperture elliptical, 

 within whitish ; columella smooth. 



Habitat : Tuscaloosa, Alabama. 



Diameter, .35 ; length, .75 of an inch. — Lea. 



The pagoda-like form of this species is especially striking in the juve- 

 nile specimens and to such an extent, indeed, that these shells resemble 

 Goniobasis catenaria Say. The carinae are very wide and turned upward 

 at the edges. The suture is deeply channelled, the fissure a mere indentation. 

 Embryo shells are about i 1-4 to 2 whorls in size, unsculptured. The first 

 two carinated whorls are scalloped by strong and regularly spaced plicae. 

 As the animal grows larger, the carinae tend to disappear so that in many 

 instances the shell is ventricose and smooth. The Wetumpka form is char- 

 acterized by revolving folds, these disappearing in up-river specimens. Mi- 

 croscopical sculpture typically gyrotomoid. 



Color varies from Ridgway's "old gold" to warm sepia. The proportion 

 of banded to unhanded shells is about five to four. The prevailing banding 

 system is four equidistant bands of the same width. The columella is rather 

 narrow, rounded, with a slight nodulous thickening above. The outer lip is 

 sharp-edged, slightly sinuous. A Wetumpka specimen measured 20 x 12 1-2 

 mm., the largest from up-river shoals, 22 1-2 x 14 mm. 



The fissure is short, straight and bluntly rounded at the opening in old 

 shells. It is seldom more than 3 mm. in depth. Compared with the fissure 

 in pumilum that of pagoda is shorter and more flaring; apparently it is 

 always straight. 



