106 THE CHICAGO ACADEMY OF SCIENCES. 
impressed; cavity of the beaks shallow; nacre pearly white, iri- 
descent, especially on the posterior part. ~ 
Length, 57 00; height, 30.00; breadth, 20.00 mill. (7386). 
- 55.50; 1s 2 -B0.00; £ 20.00 ‘* (7385). 
43.00; ‘+ 23.00; - 15.00 ‘* (7884). - 
Animal: Generally whitish, inclining to flesh color; anal 
opening rather small, not provided with papille; branchial 
large, papillose; mantle yellowish or flesh colored, edged with 
brown; ctenidia short and wide, elongately rounded behind and 
obtusely rounded before, the inner gill the larger, united above 
throughout their entire length; foot long and tongue shaped, 
muscular; labial palpi tongue shaped, small, yellowish, united at 
base; abdomen yellowish; siphons brownish; heart pulsations 
fourteen, regular. The posterior part of the outer branchium is 
modified to form a marsupium. 
Distribution: New York west to Illinois, Michigan south 
to Louisiana and Texas. 
Geological distribution: Pleistocene. 
Habitat: Found in lakes and rivers, in a few feet of water, 
on a sandy or muddy bottom. 
Remarks: A distinct little species, distinguished by the in- 
terrupted rays, which appear to be concentric lines of square 
dots in some specimens. In a few specimens examined the rays 
were not broken, but were entire and gradually increasing in 
width as they neared the ventral border. This is one of the 
most common species found in this area, and also one of the 
most beautiful. It is widely distributed. 
34. Lampsilis spatulatus Lea, pl. x., fig. 5; pl. xiii., fig. 2. 
Unio spatulatus Lea, Trans. Amer. Phil. Soc., Vol. X , p. 80, pl. viii., fig. 
22, 1845. F 
Shell: Elliptical, compressed, thick and heavy, rounded 
before, triangular behind; dorsal and ventral borders curved; 
surface roughened by the lines of growth which form scales on 
the ventral border; umbones depressed, inflated, light brown in 
color, marked by seven or eight delicate, wavy ridges; anterior 
umbonal slope rounded; posterior slope long and almost flat, 
slightly angled; ligament short, wide, stout, very dark chestnut; 
epidermis dark yellowish brown, or greenish yellow, marked 
with rather wide, uninterrupted dark green rays, which are more 
distinct on the center of the shell than elsewhere; cardinal 
