FRESH-WATER MUSSEI^S AND MUSSEIy INDUSTRIES. 29 



river. Our collections have been principally from the Cumberland, Clinch, and Holston 



Rivers. 



The Higgin's eye, Lampsilis higginsii (Lea) (PI. XIV) '^ is a rather uncommon 

 species, but a few may be found in almost any carload of mixed shells from the Ohio or 

 Illinois Rivers, or from the middle section of the Mississippi River. The nacre is often 

 yellowish or pinkish, but white shells are of first grade, with good thickness and luster. 



Lampsilis orbictdata (Hildreth) (PI. XIV) very closely resembles Lampsilis higginsii, 

 but is more southern in its distribution. Its qualities are about the same as those of the 

 preceding species. 



The fat mucket or Lake Pepin mucket, Lampsilis luteola (Lamarck) (Pis. I, XV 

 and XVI), would not have been classed some years ago as an important commercial 

 shell. Now, since the Lake Pepin form has come into use, the species is considered 

 one of the best. It is widely distributed over the upper half of the Mississippi 

 Basin, the Great Lakes drainage, and, according to Simpson, the entire Dominion 

 of Canada east of the Rocky Mountains. Its occurrence as an economic form is quite 

 restricted. The fat mucket is rarely found in rapidly moving water but is adapted to 

 slow or still water. It is the principal shell of the lakes of the Middle West, both in 

 the Mississippi and the Great Lakes drainage, but such waters are not generally suited 

 to the production of commercial shell. The fat muckets of the lakes are usually some- 

 what dwarfed and inflated, with the shell strongly curved, and too thin to produce more 

 than one or two small blanks, if any. In some cases they might be confused with 

 dwarfed pocketbooks. The species is also found in rivers and creeks, but usually close 

 along shore, perhaps well up on the banks and out of the main current. Examples from 

 such locations generally have an inflated but more elongate form, the forward part (or, 

 in commercial terms, the butt) of the shell being thick enough for blanks, while from 

 one-third to one-half of the shell, or more, is so thin as to produce only tips at best. In 

 this form the fat mucket is sometimes much like the slough sand-shell in superficial 

 appearance. Such shells can be used, but they are not always valued highly. 



Within recent years the beds of Lakes Pepin and St. Croix have been discovered 

 commercially. These lakes yield a very distinct type of fat mucket, which is remarkably 

 even in thickness, with a surface relatively flat in males, and even in females much less 

 curved than usual. Practically the entire surface can be cut into blanks which are of 

 a suitable thickness. No other shell of any species cuts with so little waste, either as 

 to the proportionate weight of sheU that is thrown away after cutting out the blanks 

 or as to the small amount to be ground from the blanks in reducing them to a proper 

 thickness for buttons. The shell is clear white, the texture good, and the luster leaves 

 nothing to be desired. The Lake Pepin mucket brought in 1914 and 191 9, respec- 

 tively, about $20 and $35 per ton. 



In the brilliancy and the extent of the iridescent portion the Lake Pepin mucket is 

 not quite equal to the niggerhead and pimple-back, but a measure of iridescence is 

 found, and in pearly character of the nacre it is fully equal to any other. As regards 

 economy, it has been found that 14 or 15 pounds of blanks are a very good return from 

 100 pounds of niggerhead shells, while more than 20 pounds of blanks may be obtained 



« This species and the following may be more closely related to the pocketbook than to the mucket, as Ortmann holds for 

 orbiculaia. Our classification is only for shell qualities, of course. 



