THE NATURAL HISTORY SURVEY. 101 
and narrow, compressed, serrated; lateral teeth very long, lamel- 
liform, elevated, striated; connecting bridge between cardinals 
and laterals narrow, thin; anterior adductor muscle scar as wide 
as high, deeply impressed, striated, confluent; posterior adductor 
muscle scar wide, distinct, confluent; protractor pedis muscle 
scar long and narrow, deeply impressed; dorsal muscle scars 
numerous, deeply impressed, situated in the cavity of the beaks; 
pallial line impressed; cavity of the beaks shallow; nacre silvery 
white, pearly and iridescent. 
Length, 79.00; height, 32.00; breadth, 26.00 mill. <j (12442). 
Be 8/008) OU eee OO. Oo (eadey, 
Animal: Anal opening small, with many light brown papille; 
branchial opening small, papillose; palpi large, subtriangular, 
united half way posteriorly; branchiz very long, curved below, 
inner the larger, united the whole of its length to the abdominal 
sac; posterior half of the outer gill of female used as a marsu- 
pium, composed of large ovisacs with rounded bases which are 
stained black. (Simpson. ) 
Distribution: New York to Kansas, Minnesota to Texas, 
Alabama and Florida. 
Geological distribution: Pleistocene. 
Habitat: Prefers a muddy bottom where it can bury itself. 
Found in rather deep water, generally. 
Remarks: Anodontoides is frequently confounded with /uteo- 
dus, but may be distinguished by the following characteristics: 
Luteolus is never so sharply pointed posteriorly, but is rounded; 
the shell of the present species is longer compared with its 
height than is /uteo/us; the female of the /uteol/us is much more 
swollen posteriorly than is that of anodontoides. The present 
species is not as widely distributed throughout the region under 
consideration as /ufeolus, and the individuals are not so numer- 
ous. The Desplaines River and itstributaries is the only stream, 
so far as known, in which this species is found. The epidermis 
varies from a perfectly plain yellow to yellowish green, rayed 
with dark green. Thus far it has only been found in the western 
region. 
31. Lampsilis rectus Lamarck, pl. xvii., figs. 1, 2. 
Unio rectus Lam., Hist. Nat. des Anim. sans Vert., Vol. VI., p. 74, 1819. 
Unio prelongus BARNES, Amer. Jour. Sci. and Arts, Ist series, Vol. VI., 
p. 261, fig. 11, 1823. 
Unio sageri CONRAD, Monograph of Unio, p. 53, pl. xxix., 1836. 
Unio leprosus Mives, Ann. Rep. Geol. Surv. Michigan, p. 240, 1861. 
