54 Calvix Goodrich 



rirtually the whole of the operciihim. This suggests that in this species 

 the opercuhim is becoming decadent — an assumption supported perhaps b.v 

 its smallness and thinness. 



Shell measurements: 



An-culosa ligata Anthony 

 Fig. 30 

 Anculosa ligata Anth., Proc. Acad. Nat. Scl, Pliila.. Feb. i860, p. 67. 



This species is apparently confined to the last seventy-five or one hundred 

 miles of the Coosa River. Shells from the following localities are in the 

 collection brought together by Mr. Smith : 



Weduska Shoals and near the mouth of \A'axahatchee Creek, Shelby 

 County ; near the mouth of Yellowleaf Creek, Cedar Island, Higgin's Ferry 

 and The Bar, Chilton County ; Butting Ram Shoals, Coosa County ; We- 

 tumpka, Elmore County. In the Schowalter collection, I\Ir. Smith found 

 ligata in material from Buck Creek, Shelby County, which is in the Cahaba 

 drainage. Mr. Smith's label indicates that he doubts the occurrence of the 

 species in this stream. The specimens had probably been misplaced. 



Judging from the numbers of shells taken at the dift'erent stations, the 

 species flourishes most prosperously on the Weduska Shoals and in the 

 shallows of The Bar. Only two specimens were taken at \\'etumpka. 



The constriction of the body whorl which suggested to Anthony the 

 name ligata is present on all the shells examined. It is sometimes not pro- 

 nounced, as in the case of the shells from near the mouth of W'axahatchee 

 Creek ; sometimes almost channeled, as in shells from Weduska Shoals. No 

 folds or ribs are present and the only features in the nature of plicae or 

 tubercules are irregular nodes near the suture, present only rarely. Striae 

 parallel with the peristome are crossed by fine lines, usually continuous, 

 which are often wavy. Under the glass, the epidermis has the appearance 

 of woven linen. The revolving lines are best shown by half-grown individ- 

 uals and are stronger near the suture than upon the base of the shell. 



Seven different banding arrangements were observed, the usual one being 

 a heavy band at the suture, at periphery and upon the base. The ratio of 

 banded specimens to unhanded is about five to one. Though ordinarily the 

 bands upon the epidermis are broken into squares, within the aperture these 

 bands are usually continuous. In only two specimens does the coloring 

 matter of the bands coalesce so as to darken the aperture. 



