108 THE CHICAGO ACADEMY OF SCIENCES. 
GROUP OF LAMPSILIS LIGAMENTINUS. 
35. Lampsilis ligamentinus Lamarck, pl. xvi. 
Unio ligamentina Lam., Animaux sans Vertebres, Vol. VI., p. 72, 1819. 
Unio ligamentinus Lam., Animaux sans Vertebres, Vol. VI., p. 533, 1888. 
Unio crassus Say, Nich. Encyc., Amer. Ed., Art. Conch., pl. i., fig. 8, 1816. 
Unio carinatus BARNES, Amer. Journ. Sci. and Arts, Ist series, Vol. VI., 
pp. 126-259, pl, ii., fig 10, 1828. 
Unio ellipticus BARNES, Amer. Journ. Sci. and Arts, Ist series, Vol. VI., 
pl. xiii., fig. 19, 1828. 
Unio fasciatus RAFINESQUE, Conrad, Monograph of Unio, p. 3, pl. i., 1836. 
Unio upsont Marsu, Mss. vide Cau, Trans. Acad. Sci., St. Louis, Vol. 
VIL., p. 23, 1895. 
Shell: Large, compressed, thick and heavy, elliptical, 
rounded before and biangulate behind; dorsal and ventral mar- 
gins rounded; surface smooth and shining in the young and 
with raised line of growth in old specimens; the shell is much 
thicker anteriorly than posteriorly; umbones not prominent, a 
little swollen, brownish in color, and marked by seven or eight 
fine, undulating, concentric folds; in old specimens the um- 
bones are eroded; anterior umbonal slope rounded, posterior 
slope forming an angle; ligament rather long, thick, very dark 
chestnut color; epidermis yellowish or light greenish with nu- 
merous dark green rays extending from the umbones to the ven- 
tral border; old specimens are very dark; the rays vary in 
width from very narrow to broad stripes; cardinal teeth double 
in both valves, those in the left valve about equal, triangular, 
crenulated; the anterior cardinal in the right valve very small, 
the posterior large, triangular, crenulated; lateral teeth strong, 
heavy, elevated, lamellar, crenulated, curved toward the ventral 
margin; connecting plate smooth, arched, rather thick; anterior 
adductor muscle scar deeply excavated, a trifle longer than 
wide, strongly striated; posterior adductor muscle scar as wide 
as long, lightly impressed, confluent; protractor pedis scar wider 
than long, deeply impressed, striated; dorsal muscle scars situ- 
ated on the posterior face of the cardinal teeth and connecting 
bridge, numerous, large, deeply impressed; pallial line wide, 
impressed; cavity of the beaks of medium depth; nacre white, 
varying to bluish and pinkish, iridescent. 
Length, 72.00; height, 41.50; breadth, 23.00 mill. (12442). 
As 98 00; Do U0; “e 35.00 ‘' (12423, Kankakee River). 
Animal; Anal opening large with an irregular crenulated 
edge; branchial opening large with many small brown papille; 
palpi small, subelliptical, united one-third of the way posteriorly; 
