Anculosae of the Alabama River Drainage 23 



color material is so irregularly secreted that deposits of it coalesce and 

 the aperture is given a mottled effect. In only one shell of the col- 

 lection, taken at Cedar Bluff, has there been so much secretion of pigment 

 that the aperture is uniformly dark — indicating that what is more or less 

 common among certain species of Goniobasis and Pleurocera is rare in A. 

 dozvniei. Differences in color between shells from near the headwaters 

 and those from mid-river or lower are slight. The unhanded shells are ord- 

 inarily a bright shining yellow, those thinly banded olive brown and the 

 ones with heavy bands dark brown. In the Cedar Bluff collection shells for 

 the first time appear that carry a great deal of pigment in the body material, 

 being pinkish by transmitted light. Several more so distinquished were in 

 the lots from Center Landing, the same county. At Fitz's Ferry, shells 

 appear whose "body" color is deep red. Others were found to the point 

 where downiei disappeared from the river. This coloration is not a case of 

 bands coalescing, for bands may be distinguished against the background of 

 red. The color includes the columella, usually a porcelain white, and the 

 operculum, ordinarily maroon. 



The embryo shell seems to be only one whorl in size, usually upon the 

 same plane as in Planorbis, but not always. One young shell taken at 

 Fitz's Ferry has two folds at the periphery of such size as to suggest the 

 carina of young A. praerosa Say. 



The operculum is thin, light red to maroon. Left margin thickened, 

 slightly curved, the right margin ragged and broadly curved, the basal 

 margin rounded. Growth lines coarse, widely spaced, spreading like an 

 opening fan. The polar point is typically close to the left margin, though 

 not on the edge. The spiral lines are well defined, loosely coiled, the whorls 

 three. The smooth Leoto dozmtiei have large opercula, the left margin 

 straighter than usual, the whorls opening broadly. These opercula, to- 

 gether with shell characters, emphasize the relationship of the species with 

 formosa. In general, the operculum of downiei is lighter of color than that 

 of formosa, thinner, the spiral lines more cleanly cut. Also it is lighter 

 than the operculum of picta, wider in proportion to length and it lacks the 

 straight left margin, a pronounced character in picta. The spiral lines of 

 donmid are clear to the naked eye. A magnifying glass is necessary to 

 make out those of picta. 



Anculosa modesta H. H. Smith, new species 

 Fig. 9 



Shell: Conic, about twice as high as it is wide, having broad, flat, somewhat 

 waving folds from suture to base of body whorl. Two or three low nodules suggest 

 plicae nearly obsolete. Lines of growth delicate, regularly spaced. No revolving 

 lines can be made out with a glass of moderate power. Color brown, shining. Two 

 narrow bands becoming obsolete before the peristome is reached appear on the body 

 whorl, one at the periphery, the other just above. No bands show in the ovate, 

 bluish-white aperture. Apex eroded, only one whorl being entire. Suture not strongly 

 impressed, a little weaving near the peristome. Columella white, delicate, smooth, 

 rounded, with only small deposits of callous top and base. Peristome thin, nearly 

 straight, sharp-edged, a little broken. 



