730 
BULLETIN OF THE BUREAU OF FISHERIES 
LAKE PEPIN MUCKET 
The species, Lampsilis siliquoidea, ( Lampsilis siliquoidea pepinensis Baker, Lamp- 
silis luteola of authors) including all varieties, occurs, according to Baker (1928), 
from the Mohawk River, N. Y., west to Iowa, Kansas, and Missouri; north to Ontario, 
Michigan, and Minnesota; and south to Kentucky, Oldahoma, and West Virginia. 
It varies greatly in commercial value, the variety, pepinensis , as found in Lake 
Pepin — a widened portion of the Mississippi River between Minnesota and Wis- 
consin-being probably its most valuable form. Practically the same form, or a very 
close relative, is found in the small lakes including Cross Lake, which is connected 
with the Snake River, Minn., about 150 miles north of Lake Pepin. 
The fish on which the Pepin mucket can pass its parasitic period include several 
species of spiny-rayed fishes. In other respects, the life history of the Pepin mucket 
is essentially the same as that of the yellow sand shell. The Pepin mucket is, how- 
ever, less abundant than this last species of fresh-water mussel and ordinarily brings 
only about two-thirds of the market price of the yellow sand shell. 
Figure 15. — Median curves of growth in length for both sexes of the Lake Pepin mucket. Curves obtained by plotting 
median valves for annual length against age; that is, first year’s growth precedes formation of King I 
Two series of Lake Pepin muckets were used in the study of growth in this 
species. One lot was taken from Lake Pepin in the summer of 1926, and the other 
from Cross Lake, Minn., in 1927. Figure 15 shows the median curves for growth in 
length for both sexes of this species as found in each locality, and Table 10 gives the 
actual values. All curves are given in Figure 16, together with the location of maxi- 
mum and minimum cases for each year class as found in Cross Lake. The actual 
values are given in Table 11. 
