110 



Unio marginis Lea, Jour. Acad. Nat. Sci. Phila., 2d series, Vol. vj, p. 255, 



1868, PI. xxxi, Fig. 69. From Dougherty county, Georgia. (PI. ii, Figs. 7-9.) 



Unio coninus Lea. .Jour. Acad. Xat. Sci. Phila., 2d series. Vol. vi, 1868, 



p. 310, PI. xlviii, Fig. 123. From Flint river, (leorgia. and Neuse river, North 



Carolina. ( PI. i, Figs. 4-6. ) 



Unio veMcularis Lea. Jour. Acad. Nat. Sci. Phila., 2d series. \'ol. viii, 

 1874, p. 37, PI. xii. Fig. 34. From Lake Ocheech()l)ee. Florida. (P\. v. Figs. 

 35-37.) 



So few of the animals of tlie Uniiinirhi' have heen described that it may not 

 be superfluous to give at this place a description of the animal of Unio parms 

 (plate ii, fig. 10), based upon the examination of a fresh specimen from the Des 

 Moines river in Central Iowa. 



Animal of Unio parvus. Color of the mass, whitish ; tentacular jjortion of 

 mantle, dark brown, ending in a caruncle ; labial palps, large, white, triangular, 

 united at base and partially so over the posterior margin; external ctenidium, 

 smaller than the internal, thicker and larger at the posterior extremity, which is 

 rounded, and on the margin, which is marked by a double low of minute, white 

 papillae; ctenidia united above throughout their entire length, free below; in- 

 ternal ctenidium, white, ovate. 



The mass of the animal within the cavity of the beak is light brown owing to 

 the color of the large liver which shows through the thin tissues separating it 

 from the chamber of the ctenidia. 



The chief anatomical peculiarity is the presence of the caruncle in the female. 

 This is somewhat separated from the main tentacular mass and is supported by a 

 slender pedicel. Its function is unknown. 



To complete the history of this species the following redescription of the 

 shell of Unio pari'H.s is presented, ba.sed upon specimens collected in the Wabash 

 River, Indiana : 



Shell, small, compressed, rather thin, elliptical, rounded anteriorly and 

 slightly thicker, posteriorly triangulate in the male and occasionally sulcate in 

 the female, thinner; (fm6oMo/ slope somewhat depressed; nmhones rather promi- 

 nent, with four to five coarse undulations; epidermis, thin, olive-green over most 

 of disk, but much lighter on the umbones, striate, especially over the middle disk 

 thence to the margin ; in the young two broadening green bands often extend from 

 the umbones over the posterior slope to the posterior margin, otherwise eradiate; 

 ligament small, light brown in color, thin, rather long, but very narrow; hinge teeth 

 small, all double in the left and single in the right valve, the cardinals erect, thin, 

 lamellar, acuminate, crenulate, separating, the laterals long, lamellar, straight, 



