Thd Genus Gyrotoma 21 



waving upon the lower edge. The girdle is thread-like to rounded and thick, 

 and of slightly lighter color than the body of the shell. 



Forms are quadrate, bulbous, ovate, elongate, any one colony having 

 specimens of these shapes. Where folds occur they are low, not very con- 

 spicuous. Of 38 specimens in one lot taken at The Bar, 29 are obscurely 

 plicate upon the upper whorls, 9 are without plicae. This ratio of sculp- 

 tured shells to those lacking plicae is about the same wherever the species 

 occurs. In general the shell is of a soft silky appearance. Color is aniline- 

 yellow to mummy-brown. The commonest banding formula is three bands, 

 the one at the periphery being wider than the others. The columella in the 

 oldest specimens is heavy, broad, complete to the top and thickened at the 

 fissure. Color is usually white, but at times yellowish-white, pink or purple. 

 The sinus is distinct, pointed. The outer lip is slightly sinuous. Mr. 

 Smith's largest exciswm measured 23 x 12 mm. 



The embryo is smooth, tightly coiled. Shells developed to the fifth 

 whorl are smooth with a slight carina at the periphery; the sinus being 

 well marked ; the fissure straight, tight and about 3 mm. in depth. Partly 

 grown individuals are not so angular at the base as in most other species. 

 The whorls indicated for an adult are seven or eight. 



Shuttleworth's shells from the Coosa River were sent to him by Rugel 

 and this collector took pyramidatnm not far from the northernmost known 

 locality for excisum. It seems probable that the shell to which Shuttle- 

 worth gave the name ovoideiim came from this point or very close to it. G. 

 ellipticiim Anth. in the Philadelphia Academy, received from Anthony 

 himself, is the same as his hulhosum except that it is elongate. Bulbosum is 

 excisum in its old age, ovalis in its graceful youth. The tuberculation of 

 glans, cited by Tr>'on as if a distinguishing character, occurs rarely and 

 seems to be without significance. 



Gyrotoma lacmiatum (Lea) 

 PI. II, figs. 24 and 25 



Schizostoma laciniatum Lea, Proc. Amer. Phil. Soc, IV, 1845, p. 167; Trans. 

 Amer. Phil. Soc, X, 1848, p. 95, pi. ix, fig. 57 ; Obs. Gen. Unio, IV, 1848, p. 95, pi. ix, 

 fig. 57 ; Journ. Acad. Nat. Sci., Phi'la., V, n. s., 1862, p. 253 ; Obs. Gen. Unio, IX, 1863, 

 p. 75; Lewis, Amer. Journ. Conchol., V, 1869-70, p. 168; Tryon, Monog. Strepom., 

 ^^73, PP- XV, 359; Lewis, Fauna of Ala., 1876, p. 23. 



Gyrotoma laciniata Lea, H. & A. Adams, Genera, I, 1858, p. 305; Binney, Check 

 List, i860. No. 324; Brot, List, 1862, p. 27; Paetel, Cat., 1888, p. 362. 



Schisostoma castanea Lea, Proc. Acad. Nat. Sci., Phila., XII, i860, p. 186; 

 Journ. Acad. Nat. Sci., Phila., V, n. s., 1862, p. 247, pi. 35, fig. 50; Obs. Gen. Unio, 

 IX, 1863. p. 69, pi. XXXV, fig. 50; Lewis, Amer. Journ. Conchol., V, 1869-70, p. 168; 

 Tryon, Monog. Strepom., 1873, p. 355; Lewis, Fauna of Ala., 1876, p. 22; Hinkley, 

 Nautilus, XVIII, 1904, p. 40. 



Gyrotoma castanea Lea, Binney, Check List, i860, No. 311; Brot, List, 1862, p. 

 27; Paetel, Cat., 1888, p. 361. 



Gyrotoma olivula excisa (Lea), Hannibal, Proc. Malacol. Soc, X, 1912, p. 181. 



