32 BULLETIN OF THE BUREAU OF FISHERIES. 
firm; (3) the shape of the shell is long and straight, so that pieces suitable for knife han- 
dies 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 wandering 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 (Pl. 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) (Pl. 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 subrostrata (Say) (Pl. XTX) 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. 
