THE NAUTILUS. 127 



covering the umbilicus; columella curved, with a heavy callus and 

 obtuse tubercle in the center ; umbilicus round and deep. The 

 animal is yellowish. 



Alt. 1, diam. 2 mm. 



Types (No. 27150 Coll. Walker) from the Coosa River at " The 

 Bar" 2^ miles above Yellowleaf Creek, Chilton Co., Ala. Cotypes 

 in the collection of T. H. Aldrich, Geo. H. Clapp, John B. Hender- 

 son, Jr., and the Philadelphia Academy. 



This species resembles tantillus in being spirally striate but differs 

 in being umbilicate and in having a tooth on the columella, as well 

 as in the general shape. It does not resemble smithii in any of its 

 special features, and differs from carinatus in being more obtusely 

 carinate and in the wider umbilicus and stronger spiral striation. 



NEOPLANORBIS CARINATUS n. sp. PI. IX, figs. 17 and 18. 



Shell minute, planorboid, narrowly umbilicate, nearly flat above, 

 convex below, but obliquely flattened below the peripheral carina, 

 which is strong, but rather blunt ; pale horn-color ; lines of growth 

 fine, closely set and regular, sculptured above by a few fine sub- 

 obsolete spiral lines, stronger towards the periphery ; under surface 

 with numerous fine spiral lines heavier than on the upper. Whorls 

 2, rapidly enlarging ; apex sunken ; apical whorl somewhat flattened 

 above, convexly rounded at the periphery which, at about the be- 

 ginning of the body whorl, becomes angulate and then carinate ; the 

 body whorl above is slightly convex in the center, but flattened 

 toward the suture, and " pinched out " at the periphery to form the 

 carina ; suture well impressed, descending toward the aperture below 

 the periphery ; aperture large, much wider than high and auricu- 

 lated at the periphery by the carina ; upper and lower margins flat- 

 tened and nearly parallel ; columellar margin dilated, free, slightly 

 curved back over the small, round umbilicus, and obtusely angled 

 where it joins the basal margin ; columella somewhat thickened, 

 with a small obtuse tubercle at about the center. 



Alt. 1, diam. 2 mm. 



Types (No. 27151, Coll. Walker) from the Coosa river at Dun- 

 can's Riffle, Coosa Co., Ala. Cotypes in the collections of T. H. 

 Aldrich, Geo. H. Clapp, John B. Henderson, Jr., and the Phila- 

 delphia Academy. 



In form the species reminds one of a minute Planorbis oper- 



