340 THE CHICAGO ACADEMY OF SCIENCES. 



termediate tooth with the body perforated, and the peduncle 

 more than twice as long as the body; cusp /-denticulated, the 

 third denticle (counting from within) being twice as broad as 

 the others. Inner lateral tooth with fourteen denticles at the 

 summit. Outer lateral tooth also with fourteen denticles." 

 (Stimpson.)* 



Distribution: Central parts of North America. 



139. Somatogyrus subglobosus Say. Text figure 123. 



Paludina subglobosa SAY, Journ. Phil. Acad., Vol. V, p. 25, 1825. 

 Melania isogona SAY, New Harm. Diss., Vol. II, p. 227, 1829. 

 Paludina pallida LEA, Trans. Amer. Phil. Soc., Vol. VI, p. 22, pi. xxiii, 

 fig. 104, 1839. (Young.) 



Shell: Subglobose, solid, somewhat depressed; coloryel- 

 lowish-horn; surface shining; lines of growth fine, oblique, 

 crowded; sutures much impressed; apex small, rounded, sub- 



FIG. 123. 

 SOMATOGYRUS SUBGLOBOSUS Say. (Original.) 



hyaline; aperture orbicularly-ovate, somewhat produced at the 

 lower part, whitish inside; spire short, depressed, rounded; 

 whorls four, convex, the last swollen and all rapidly increasing; 

 peristome simple, sharp, rather thick, the terminations joined 

 by a light callus; base rounded, umbilicus small, narrowly open. 

 Length, 7.00; width, 6.50; aper. length, 5.00; width, 4.75 mill. (coll. Jensen). 



Animal: Not examined. 



Radula formula: &+$+ -J^+lf+jy (3-1-3); the cen- 

 tral tooth almost square, the lower outer corners very much 

 produced and the basal margin with a projection of a squarish 

 shape; reflection seven-cuspid, the central cusp very long and 

 sharp, reaching almost to the basal margin of central projec- 

 tion, side cusps shorter; the lateral projections of the base of 

 attachment are armed with three blunt, rounded denticles, of 

 which the highest is about three times the length of the other 



* Researches upon the Hydrobiinse, p. 21, 22. Stimpson remarks that the holes in the 

 appendage of the intermediate tooth may be simply pits. I have not been able to either 

 prove or disprove this statement. 



