Till NAUTILI'S. , 



lateral teeth and an accompanying depression in the opposing valve; 

 laterals straight with an elevated collar or ridge as an extension of 

 the lower lateral tooih and extending up to the cardinal ; cicatrices 

 confluent, cavity of the beaks very slight, nacre pale white in old and 

 flesh-colored in young. 



Diameter .75, length 1.2'), width 2 inches. 



Habitats — Altamaha, Suwannee and Flint Rivers. 



Type in National Museum. 



Remarks : Two adults were first received from the Altamaha 

 River, Liberty County, Ga. Later three others came from the 

 Suwannee River, Madison County, Fla., and still later twenty others 

 from Spring Creek, a branch of the Flint River, in Decatur County, 

 Ga. — showing quite a range, and yet in all of these places it seems 

 to be a rare shell, as so few were received in large lots of several 

 hundred. The teeth are quite large and solid for the size of the shell. 

 It is difficult to place it with any group, for which reason comparisons 

 would seem out of place. The younger specimens bear some resem- 

 blance to simulans or nux, but it is less inflated in the umbonal re- 

 gion, and more compressed or flattened and pointed behind than 

 either of them, and is also more oblique or inequilateral. It lias 

 heavier and blunter umbos and beaks than N. perovatus Con., and 

 also a straighter base and less pointed behind. 



We dedicate this species to Prof. George W. Harper. Principal of 

 the Woodward High School, of Cincinnati, 0. 

 U. TinKerl, sp. nov. 



Shell black above, shading off' to a lighter color posteriorly and 

 around the base, covered with close elevated growth lines ; nearly 

 circular, somewhat inflated : ray less, except in the very young, which 

 are covered with fine green rays ; bluntly pointed behind, gracefully 

 and continuously curved in front up to the dorsal margin ; dorsum 

 arched ; base abruptly extended near its center by reason of the 

 broad, rounded ridge which extends from umbo to base ; cardinal 

 teeth solid, direct and double in both valves ; lateral teeth double in 

 the left and single in the right valve, heavy, somewhat curved, very 

 deeply indented and coarsely serrated ; beak cavity considerable and 

 very angular, anterior cicatrices separated by a mere thread, posterior 

 cicatrices confluent ; nacre white or slightly flesh-colored. 



Diam. 1, length 1.50, width 1.75 inches. 



Habitat : Tombigbee River, Alabama. 



