22 



Calvin Goodrich 



Description : Shell smooth, obtusely conical, rather thick, banded, yellowish 

 horn-color; spire obtuse; sutures excavated; whorls convex; fissure deep; aperture 

 elliptical, whitish within; columella smooth, thickened above. 



Habitat: Tuscaloosa, Alabama. 



Diameter, .25 ; length, .45 of an inch.— Lea. 



This is the smallest species of the genus. The largest shell examined 

 measures 16 x 10 mm. The average size of fourteen speciinens is 14.9 x 

 8.5 mm. The species resembles excisum Lea in sculpture, fissure and 

 banding system. It occurs from Fort William Shoals, Talladega County, to 

 Wetumpka, Elmore County. A note by Mr. Smith with lacinialtim from 

 Fort William Shoals reads, "Found in a few places along the eastern or 

 Talladega County side and quite close to the banks where the water is 

 swift; on or clinging to the lower side of stones. In one place, partly 

 under overhanging bushes, we collected over 100 within a few yards, but 

 generally the species is rare." 



In laciniatum the fissure is very deep in porportion to the shell; it is 

 narrow and hugs the body whorl. Its depth in adults is 7 to 7>^ mm. The 

 girdle is small and thin. Of 48 specimens the girdle is absent in 13. 



The shell is conic, subangulated, with whorls flat to slightly convex. Up- 

 per whorls are smooth to carinate, showing a tendency to form a few ob- 

 scure plicae. Commonly there are four or five low folds upon the base, 

 seldom very distinct. Beneath the fissure are low vertical puckerings, made 

 conspicuous by spots of coloring matter between them. Growth lines are 

 fine, irregular, crossed on parts of the shell by revolving lines which in 

 few instances go clear around the whorl. Color is buckthorn-brown to 

 clove-brown. The prevailing banding formula isi four bands of equal 

 width, the two in the center approximate. These latter bands sometimes 

 coalesce into the formula ordinarily occurring in excisum. The aperture 

 is elliptical, nearly pointed at the top, more rounded at the base and having a 

 slight sinus. The columella is small, regularly rounded, white and having 

 a node at the fissure. In only one specimen observed was the columella 

 developed fully above the center. The outer lip is sinuous, more angular at 

 the top than rounded. 



The embryo shell is very small, smooth, tightly coiled. Some juveniles 

 are strongly carinate, others smooth. Irregular plicae occur. There are 

 three bands, that at the center dividing into two. In shells of five whorls 

 the fissure is quite deep. The adult laciniatum has seven or eight whorls. 



A comparison of the types of laciniatum and castaneum proved them 

 to be identical. Lea's first specimens were apparently from Wetumpka. 

 It was not until about fifteen years later that he saw the up-river forms. 



Group op Gyrotoma incisum 



Cylindrical to globose; whorls shouldered, often constricted, sometimes 

 nodulous ; smooth to striate ; fissure usually shallow and oblique though 

 in amplum as deep as 9 mm. and in instances straight; girdle stout and ir- 

 regular when present; aperture ovate; sinus more noticeable in young than 

 in adult shells ; bands three. 



