68 THE CHICAGO ACADEMY OF SCIENCES, 
Animal; Generally brownish or yellowish brown in color, the: 
mantle spotted with dark brown; ctenidia wide, not long, 
broadly rounded before and behind, united above and to the 
opposite pair throughout their entire length, brownish white in 
color; labial palpi of the usual shape, large, coarsely laminated 
inside, attached at base, dark yellowish brown in color on the 
inside, and light yellowish on the outside; foot large, dark 
flesh color shading into whitish on the abdomen; siphons 
yellowish white inside, changing to brownish and finally to 
black on theedge of the tentacular portion; anal opening minutely 
papillose; branchial with large papille: between the beaks and 
the pericardium the animal is pinkish. Heart pulsations regular, 
numbering ten to eleven per minute. The heart was seen beating 
for nearly half an hour after the animal was removed from the 
shell. The outer gill of the female is used asa marsupium and 
is filled with “‘ ovisacs which run crosswise with the gill.” 
Distribution: Southern Canada, northern and central por- 
tions of the United States. 
Geological distribution: Pleistocene. 
Habitat; Found in the larger lakes and rivers, on a muddy 
bottom, in water from two to fifteen or more feet in depth. 
Remarks: A widely distributed species, at once distinguished 
by the semidentate margin and coarse umbonal sculpture. 
When the interior is tinged with salmon it is one of our most 
beautiful shells. Some forms have the umbones a trifle ele- 
vated, and when in this state they greatly resemble some forms of 
pavonius (see remarks under that species). The rays are very 
variable and may be very distinct or hardly visible, and there is 
also considerable variability in width. 
10. Strophitus pavonius Lea, pl. iii., fig. 5; pl. v., fig. 3. 
Anodonta pavonia Lea, Trans. Amer. Phil. Soc., 2d series, Vol. VI., p. 
78, pl. xxi., fig. 65, 1839. , 
Anodonta wardiana Lra, Trans. Amer. Phil. Soc., 2d series, Vol. VI., p. 
46, pl. xiv., fig. 42, 1889. 
Shell: Somewhat solid, a little inflated, elliptical, rounded 
before and acutely rounded behind; dorsal margin almost 
straight, ventral margin slightly rounded; surface smooth, 
marked by fine lines of growth; umbones elevated, inflated, 
light straw colored, marked by three strong elevated undulations, 
the apex directed anteriorly; ligament rather strong, dark horn- 
color; epidermis yellowish green, with light green rays extend- 
ing from the umbones to the ventral margin; hinge line thick- 
