134 THK NAUTILUS. 



Lewis had not given any critical study to the grouj), and tiiat his 

 determinations were at the best superficial. It is of interest there- 

 fore to consider his list seriatim, and to make such corrections as are 

 necessary. S. aureus. Dr. Lewis confounded this species with S. 

 parviUus Tryon and georgianus herein described. For the first error 

 he is not wholly responsible, as the only genuine parvuhis he had 

 was received from Dr. Lea as aureus. His specimens from the 

 " Tennessee River" and " Cahawba River " are georgianus. Those 

 from the Coosa are partly georgianus and partly aureus. Those from 

 the Alabama river are correctly named. 



It may be added that aureus was found in the Coosa at Wetumpka 

 by Mr. Hinkley, where it has also been collected by Mr. A. C. 

 Billups. It is also in the Lewis collection from the Holston river, 

 Tenn., the Etowah river, Ga., the Tennessee river, Jackson Co., 

 Ala., and from Bridgeport, Ala. It was also collected by Dr. Pils- 

 bry and myself in the Tennessee river at Knoxville, Tenn., on our 

 return from the Pentadelphian expedition in 1901. I have it also 

 from Decatur, Ala., collected by De Camp. 



S. currierianus, Dr. Lewis' specimens from Decatur, Ala., are 

 labelled " Type " and seem to be correct. See PI. v, figs. 8 and 9. 



5". parvulus. As stated above, the only specimens referable to 

 this species (see PI. v, figs. 22 and 23) from the Connesauga river, 

 Ga., were received from Dr. Lea under the name of aureus. His 

 specimens from the Tennessee river at Bridgeport, Ala., are imma- 

 ture aureus, as are also those from the Coosa. 



S. suhglobosus. There are no specimens under this name froni the 

 Coosa river in the Lewis collection. Those from the Alabama river, 

 while differing somewhat in contour from the typical form of the 

 Ohio valley, seem substantially the same. 



The characteristic feature of the Coosa river species of Somatogy- 

 rus is the heavy flat columellar callus, which usually quite obliterates 

 the umbilicus. This is present in nearly all the species. The 

 former connection of the Coosa with the Tennessee drainage is shown 

 by the occurrence of S. subglobosus, aureus and georgianus in both 

 systems and the narrow, rounded columellar callus in S. obtusus and 

 umbilicatus, which is characteristic of all the species of the Ohio and 

 Tennessee drainage, except ^S". georgianus and the form referred to 

 »S'. cun-ierianus by Tryon in Mon. F. W. Univ. Moll., p. G2, PI. 17, 

 fi£. 13. 



