Anculosae of the Alabama River Drainage 53 



Anculosa vlttata Lea 

 Fig. 29 

 Anculosa vittata Lea, Proc. Acad. Nat. Sci, Ph'da., xii, p. 188, i860. 



This species was described by Dr. Lea as from the Coosa River at We- 

 tumpka. Air. Smith does not seem to have found it there. As there are no 

 specimens in the Schowalter collection it is highly probable that the occur- 

 ance of zittata in this locality is extremely rare and that the few shells 

 of Dr. Schowalter's finding passed out of his hands. Thirty or forty miles 

 north, however, where the Coosa borders Chilton County Mr. Smith found 

 the species in quantity, his three localities for vittata being The Bar, Hig- 

 gin's Ferry and Duncan's Riffle. A note with the lot from The Bar reads 

 "swift water.'' 



Considering the variability of most of the Anculosae of the Coosa, the 

 characters of I'ittata are remarkably constant. The sculpture consists of 

 very fine, hair-like lines of growth and occasional revolving lines which 

 are noticeable only near the suture. These latter lines on the upper whorls 

 of a few specimens are strong enough to suggest carinae. The rest scars, in 

 keeping with the sculpture mentioned, are unusually delicate. 



The color varies from yellow to rusty brown, the shells being dull rather 

 than shining. The prevailing arrangement of the well-marked bands is a 

 band hugging the suture, a band at the base and two bands, rather close to- 

 gether, at the periphery. Nine other arrangements were noted in this study, 

 but they are all modifications of the prevailing formula. 



The columella is very flat, broad, the outer edge raised above the body 

 whorl. This edge is crescent-shaped as viewed from the side. The inner 

 margin is slightly angled at the center rather than curved, and it here has 

 the mere suggestion of a tooth as in A. melanoides Conrad, this character 

 being more pronounced in material from The Bar than elsewhere. The 

 columella is white to bluish-gray, in some specimens purple. The peristome 

 is sharp-edged, firm, usually straight or having only a slight curve close to 

 the suture. 



It would appear that z-ittata is not as much exposed to erosion as most of 

 the Anculosae, for entire specimens occur in this material much more than 

 in others. The nuclear whorls are tightly to loosely coiled, smooth, elevated. 

 The development of the shell is so regular that it is impossible to discover 

 the dividing line between the embryo whorls and those which follow. So 

 far as A'Ir. Smith's collection shows, the adult has not to exceed four and 

 one-quarter whorls. 



The operculum is very small, oval, thin, transparent, yellow to brown. 

 The left margin is firm and curved only slightly less than the thin and torn 

 right margin. The basal margin is worn and irregular as if from rubbing 

 against the columella. The polar point is scarcely more than an indenta- 

 tion at the base of the left margin. The spiral development does not show 

 up even under a fairly strong glass. Growth lines are light. In most oper- 

 cula of this genus, the area of attachment occupies as a rule not more than 

 one-half of the operculum. In the case of zittata it appears to involve 



