115 



south Tt'iuu'ssee and in tlie lUack Warrior River ol Alabama. The heaviest, 

 largest and glans like forms from the soutli occur in the Coosa River, a tributary 

 to the Alabama, just above \Vetumi)ka. Similar shells were taken in numbers in 

 the Cahaba River, in Bibb County, also tributary to the Alabama. 



Uxio AM(iDA],UM Lea. 



Observations on the Genus Unio, Vol. IV, p. 33, pi. XXXIX, tig. 1, 1843, 



from Lake George, Florida ; Trans. Am. Phil. Soc, '2d Ser., Vol. IX, pi. 39, fig. 



1, pp. 275, 276. See also Simpson, " Notes on Florida Unionida^," Proc. U. S. 



Nat. Mus. Vol. XV. pi. LXVII. tig. 3. p. -i2(i, 1S92. 



I'nio papyraceiis (lould. Proc. Bost. Soc. Nat. Hist.. Vol. II, p. 53, 1845. 



Florida. Latin diagnosis ; no figure. 

 The following description of I'nio amc/dalnm is based upon excellent speci- 

 mens from the original locality. 



Shell small, striate, somewhat inflated, nearly oval in outline, rounded be- 

 fore, subangular posteriorly, viewed dorsally the outline is rounded cuneate pos- 

 terior to the umbones, female slightly emarginate on the ventral border ; 

 epidermis striate, light straw colored over the disk, greenish to greenish-yellow 

 near the ventral mai-gin, faintly rayed on the posterior dorsal slope in the manner 

 characteristic of all the parvus group; ligament short, thin, light horn-colored; 

 lines of growth distinct, broad, and much darker than the balance of the disk; 

 anterior or cardinal teeth double in the left and single in tlie right valve, though 

 an occasional specimen exhibits a tendency to double teeth in both valves, flat- 

 tened, plate-like, crenate; posterior teeth double in the left and single in the 

 right valve, long, lamellar, straight, striate, particularly toward the extremities; 

 anterior cicatrices distinct, the adductor rather deeper or impressed, that of the 

 protractoi pedis rather large, oval, but slightly impressed ; posterior cicatrices con- 

 fluent, scarcely impressed, very iridescent ; cavity of the beaks rounded and shal- 

 low, with a row of pit-like and minute cicatrices just under the dorsal plate; 

 nacre white, pinkish or salmon tinged towards the cavity of the beaks, beautifully 

 iridescent over the entire posterior half, but the play of iris-like colors is most 

 marked on the posterior margin beyond the ])allial cicatrix, which is very faintly 

 impressed. 



The average dimensions are: Length, 3.1 mm.; width, 1.22 mm.; heighth, 

 1.82 mm. 



Some specimens of this shell approach the form of ('nio minor Lea in that the 

 cardinals are much heavier tlian usual and the substance of the shell is much 

 thicker; in these forms also the posterior teeth are incrassate. The tout enst-mbie 



