32 BULI.ETIN OF The bureau of fisheries. 



firm; (3) the shape of the shell is long and straight, so that pieces suitable for knife han- 

 dles or other novelty objects can easily be cut from it; and (4) the comparative uni- 

 formity of thickness and the light hinge make the shell yield the best return in proportion 

 to its weight. 



This species is found in small quantity mixed with other mussels in the principal 

 mussel beds or on the more sandy or gravelly shoals. It seems also to live well in 

 muddy bottoms. 



Like others of the genus, it is a long-term breeder, but is, so far as known, very 

 restricted in parasitism. No other hosts than the several species of gars seem to carry 

 it well, but there is reason to believe that the large-mouth black bass may also serve as 

 host. It is a peculiar fact that the two species of most restricted parasitism are the 

 niggerhead and the yellow sand-shell. We know only one host for the niggerhead, 

 yet it is a very abundant mussel; there are several species of gars, and they are quite 

 plentiful; but the sand-shell is never very numerous in any locality. 



A noticeable characteristic of the yellow sand-shells is the habit of v/andering about 

 on the bottom; for they travel more than the mussels of any other species. The yellow 

 sand-shells are frequently observed to crawl up on the shoals with the rising water, and 

 it is common report that after the subsidence of floods they may sometimes be found 

 far out in the swamps. 



The sand-shell has a relatively rapid rate of growth, probably attaining a market 

 size in four to six years. Its growth is undoubtedly more rapid in the South, as in Arkan- 

 sas, than in the North. If any species should prove adapted for commercial rearing in 

 private waters, it would seem that the yellow sand-shell and the Lake Pepin mucket 

 offer the best promise. 



The slough sand-shell, Lampsilis jallaciosa (Smith) Simpson (PI. XIX), is 

 similar to the yellow sand-shell but is generally smaller and rather too thin. Its 

 geographic range is wide, and it is said to have been much more abundant formerly 

 than now. There are few places in which the slough sand-shell is at all numerous. It 

 is common in the lower part of the Illinois River, and is a very familiar shell in the 

 Wabash River, where it is mistakenly called bank-climber. 



The black sand-shell, Lampsilis recta (Lamarck) (PI. XIX), is also widely distributed 

 in the Mississippi River and the Alabama River drainages, the Red River of the North, 

 and the St. Lawrence system. It is found principally in the upper part of the Missis- 

 sippi Basin. 



The shell is generally more compressed and heavier than the other sand-shells. 

 The nacre has an excellent surface, but its economic qualities are variable. Often the 

 nacre is deeply colored, pink, salmon, or purplish. White shells are the rule in the 

 Mississippi and in some other streams, and many of them are of very superior quality. 

 They were sometimes exported with the yellow sand-shell. The black sand-shell has a 

 peculiarly good luster and pearliness and even iridescence; some of the most beautiful 

 specimens the author has seen were, however, condemned by manufacturers as too brittle 

 and as otherwise inferior. 



Lampsilis suhrostrata (Say) (PI. XIX) might sometimes be confused with the black 

 sand-shell or more easily, perhaps, with very dark-colored slough sand-shells. It is 

 entirely too thin to be of value. 



