Anculosak of Trie Alabama River Drainage 25 



Anciilosa taeniata (Conrad) 

 Fig. 10 



Anculotus taeniatus Conrad, New Fresh Water Shells of U. S., p. 63, 1834. 



This species has the longest range of any of the Anculosae of the Ala- 

 bama system. Conrad described it from Clairborne, which is much nearer 

 to the Gulf of Mexico than it is to the mouth of the Coosa River. Mr. 

 vSmith collected it as high on the Coosa as the northeastern point of St. Clair 

 County and on all the big shoals below as far as Wetumpka. Material in the 

 Schowalter collection is credited to the Cahaba River. It has been taken 

 at Selma on the iVlabama below the mouth of the Cahaba. Doubtless it 

 could be found in favorable locations between this place and the type locality 

 at Clairborne, and possibly beyond. 



The variation in taeniata, while considerable, is not as confusing as 

 that of several others of the species under consideration. There appear to 

 be no more than a few clearly traceable offshoots. In form the species is 

 heavy, subangular, usually shouldered or humped, often longitudinally pro- 

 duced. Lines of growth are very fine and close together. These are crossed, 

 though not in the case of all shells, by revolving lines which are usually 

 discontinuous and often undulate. Viewed under a glass this sculpture, 

 when well marked, gives the surface of the shell the appearance of peach 

 down. Shells with folds mostly confined to the shoulder appear in nearly all 

 the lots, these being more common in material from the, lower part of the 

 Coosa than from the upper. Of 81 taeniata from Ten Island Shoals, St. 

 Clair County, 64 were smooth, 17 had folds at the shoulder. Out of 74 from 

 The Bar, Chilton County, the smooth shells numbered 56, those with folds 18. 

 Yet there is actually no striking change in sculpture from the St. Clair 

 County stations to Wetumpka. 



The columella of taetiiata is usually fairly stout, smooth, rounded, reg- 

 ularly developed and lacking the "buttressed" callous present in the equally 

 large A. forniosa Lea and foremani Lea. In old specimens of taeniata 

 the face of the columella is sometimes ground down as if against the rocks, 

 so as to give it the flattened appearance characteristic of some of the other 

 species of Alabama Anculosae. Changes in the color of the columella from 

 north to south were observed. Of 81 shells from Ten Island Shoals, 58 

 had the white columella, 5 were pink, 18 were streaked or spotted with 

 purple or brown pigment. The columellae of the Truss Shoals shells were 

 purple without exception. At the Three Island Shoals, the white colum- 

 ella became rare and at Ft. William Shoals one lot of 70 shells had only 

 one specimen with a white columella. The columellae of Weduska Shoals 

 material were purple or reddish while those of the shells from The Bar were 

 all purple. The few shells from the Cahaba in the Schowalter collection 

 had the white columella slightly touched with color. Fading in these spec- 

 imens was marked. 



The peristome of this species is ordinarily straight, sometimes slightly 

 curved close to the suture; strong, sharp-edged. 



The upper river shells are yellowish to olive-brown, the bands being well 

 defined. Material from the lower part of the Coosa are much darker, less 



