42 BULLETIN OF THE BUREAU OF FISHERIES. 
The variable quality of the several species of mussels is discussed on page 16 of Part 
I in connection with the commercial qualities of shell. Only a word is necessary in this 
connection in regard to the geographic aspect of the subject and its effect upon the 
fishery. The profitableness of shelling in any locality is determined largely by the 
quality of the more abundant species. Some species are nearly always rare, or, at least, 
are never the dominant species of mussel beds. Nevertheless it is a striking feature of 
the mussel fishery that in different streams or in different portions of the same stream 
different species may dominate. We may have niggerhead streams, mucket streams, 
pig-toe streams, etc., but we do not expect to find maple-leaf streams, buckhorn streams, 
or butterfly streams, although these forms are widely distributed. 
In that portion of the Mississippi constituting Lake Pepin, the Lake Pepin mucket 
comprises as much as 60 per cent of the catch from many beds, in spite of the large 
number of other common species present. Since this shell as found in Lake Pepin is 
of the best quality in so many respects, the region of the lake may be expected to be 
the scene of active fishery as long as the beds are reasonably productive. 
Certain portions of the Mississippi River may show from 50 to 85 per cent of 
niggerheads against all other species combined. At Le Claire, Pleasant Valley, and 
other points above Davenport, Iowa, 75 or 80 per cent of niggerheads are reported. 
Counts of shell piles above Keokuk, October, 1912, showed 80 per cent niggerheads, 
and 10 per cent monkey-faces, while 7 other species constituted the remaining 10 per 
cent. There were a few discards not included in the count. A similar predominance of 
niggerheads is observed in Arkansas, especially in the White and St. Francis Rivers. In 
the St. Francis near Madison, Ark., in 1913, about 16 species were taken, but 75 per cent 
were niggerheads. In such regions one may expect a steady fishery until the beds are 
nearly exhausted. It is reported that in the lower Pearl River of Mississippi and Louisi- 
ana the niggerheads constitute more than 99 per cent of the mussels in beds that have 
been fished, but the quality of the shell has not been definitely ascertained; if the report 
of percentage is correct, these beds are the most remarkable known for the predomi- 
nartice of one species. 
In the Illinois River Danglade ¢ found that in various beds blue-points may con- 
stitute 50 to 60 per cent of the catch, washboards 23 to 50 per cent, and warty-backs 
as much as 31 percent. His observations regarding the river as a whole are succinctly 
expressed by the statement: “The Illinois is distinctly a washboard, blue-point, and 
warty-back river.”’ 
In piles of shells taken near Havana, Ill., washboards and blue-points constituted 
95 per cent of the shells, while nine other species constituted the remaining 5 per cent. 
The fortune of the fishery in this stream will necessarily fluctuate with the demand 
for that class of shells, which is not at all constant. At times there may be a strong 
demand for blue-points and washboards for the making of buttons of the larger sizes; 
but, except with such a demand or with an excessive call for the higher-class shells, 
the market will not be the most favorable. 
In the Ohio River, the Ohio River pig-toe may constitute as much as 80 per cent 
of the mussels of a bed, but this species is never in high favor; mixed in with the pre- 
dominant species, there is always a certain number of mussels of other species, some of 
which may be of superior quality. 
@ Danglade, Emest: The mussel resources of the Illinois River. Appendix VI, Report, U. S. Commissioner of Fisheries 
for 1913, 48 pp., 6 pl. including 1 map. Washington, ror14. 
