44 BULLETIN OF THE BUREAU OF FISHERIES. 
strictly comparable to those in the preceding table, since the preceding table is based 
upon the shells taken from the river, and many of the smallest shells are lost before 
reaching the factory. 
Average size 
Pairs of 
Species. Locality. ehells 
on 
Length. | width, | °™ 
Inches. Inches. Number. 
Blue Moint Hes ae ew seth aod ve Mississippi River, Grafton, Ill.............. 00.0005 3-82 2. 81 4) 500 
LOTS earn aac enOb. basse aro > Sunflower! River, Miss). 0 =. 0- vecmep uneh veces 3-50 2.56 5,500 
Butterhy.. AIS. F<. Jorn | White Rivet) Ark.) i 0. 20h cee. odes 3-00 2.44 9,000 
Lake Pepin mucket.. ....| Mississippi River, Lake City, Minn... 3-17 1.92 10,000 
Maple-leaf........... ....| White River, Ark 7 DA BNL 2-54 2.00 II, 000 
Monkey-face........ ....| Mississippi River, Fairport, Iowa... . ee 3-00 2. 43 8,000 
Mucket...... Airey see BENE Sree aecsoace adie aa 4:67 2.80 6, 800 
Do.. = : 4-47 2. 60 5,000 
Do.. .| Wapsie River, Waverly, Iowa . 4-98 2-95 5,500 
Niggerhead .| Mississippi River, Fairport, Iowa ae 3-56 a. 81 4,000 
DOU. cise ....{ Sunflower River, Miss ...............005 ad 2-95 2.20 6,500 
BOGS cat as ....| White River, Ark....... as a 2.58 2.14 9,000 
Pig-toe....... B do apr 2.23 2.00 13,000 
Pimple-back. : 2.10 2.00 16,000 
Pocketbook. . 7 Sa 490 3°35 5,000 
TOG acpeo ....| Wapsie River, Waverly, Mayas ce stieaedsccho nae 5-10 3-29 4) 000 
Three-ridge............ sia A] OM RRA VER ) WWAS ceil ct clots aniardia ite Hee Bee 4-33 3-33 ‘Ay 800 
wegbout ak Ari Mississippi River, Fairport, Iowa....... a5 5.75 412 2,000 
Wale eeaitme sites ....| Mississippi River, Grafton, Ill........... is! 4: 40 3-10 4) 500 
Yallow sand-shell. . ....| Mississippi River, Fairport, Iowa....... oa 4°72 2-33 6,000 
POs e eeadeitassnene panealar cise ers acs GO iss atacctuving eiteins stolonle stepisis's onto s atalino orate = eis 4-23 2.00 9,000 
Many of the shellers are nomadic and therefore move readily with their launches 
from a region of poor fishery to a better locality. It is often the case, however, that in 
times of low water, when the mussels are easily obtained, the farm hands, miscellaneous 
laborers, and others engage temporarily in shelling, using any kind of available 
equipment or collecting by hand. It is in such cases that good beds are often rapidly and 
seriously depleted. 
A noteworthy difficulty encountered in some places where the quality of shells is 
good is the high cost of transportation. In regions remote from manufacturing centers 
it is therefore advisable to have cutting plants, so that the expense of shipping the waste 
portions of the shell may be obviated. A cutting machine costs about $16. The cost 
of a plant of 12 machines, complete, with all equipment except power, was about $400, 
as computed in 1914. In 1919 a cutting machine of improved type sells for $28 anda 
12-machine outfit is estimated at $725.% 
DEPLETION OF THE MUSSEL RESOURCES. 
It has been mentioned that the extension of the fishery has been directed by the 
depletion of the mussel beds in the regions first worked. Generally speaking, it may be 
said that no stream or region has been entirely exhausted, but wherever a mussel fishery 
has once existed it has continued in operation tg this time, although in reduced activity 
and with much irregularity. 
The history of a shell bed in typical cases may be described. When first fished, 
there is usually a large proportion of very old shells which are coarse and heavy and often 
much eroded. After the first year or two the yield of the bed is chiefly the medium- 
@ In referring to values and costs the writer feels obliged throughout this paper to give figures, when available, for both the 
years 1914 and 1919. While it can not be assumed that prices of 1919 are normal, it seems reasonably sure that prices will not 
return to the level of 1914. 
