FRESH-WATER MUSSELS AND MUSSEL INDUSTRIES. 27 
mother-of-pearl of the ocean. The washboard spawns in the late summer and early 
fall. 
In places in Florida, Georgia, and Alabama heros is replaced by Quadrula boykiniana 
(Lea). 
The bank-climber, Quadrula trapezoides (Lea) (Pl. XII), should be mentioned in 
this connection. It is found in streams flowing into the Gulf of Mexico, from Alabama to 
Texas, and northward in the Mississippi system to Tennessee and Arkansas. The shell 
has a deep purple nacre and is quite valueless for manufacture. Possibly it yields a 
proportion of pearls. It isavery familiar shell in Louisiana, Arkansas, and eastern Texas. 
The buckhorn, Tritogonia tuberculata (Barnes) (Pl. XI), is, perhaps, better named 
in connection with the washboard than anywhere else. It has a naturally white nacre 
of good texture and quality, but is often spotted. It is thinnish at the tip and has a 
very rough back; some shells have a pinkish tinge. It has also been called pistol-grip, 
a name appropriate to the form of elongate examples. There is a short form character- 
istic of males and a much more elongate form common to females. It is found widely in 
the Mississippi and Gulf drainages and is reported as a summer breeder. 
LAMPSILIS CLASS. 
Such familiar and valuable shells as the mucket, the Lake Pepin mucket, and the 
sand shells are representatives of this class of mussels. In many respects they are quite 
distinct from the Quadrulas. 
In commercial quality there is a wider range, not only between the species composing 
the class, but even within the individual species in most cases. The highest-priced shells 
of all are of a Lampsilis species, while some of the most worthless paper-shells are species 
of the same genus. Muckets may possess excellent qualities, or again they may be 
pink or otherwise inferior; some pocketbooks are good, some are worthless. Fat 
muckets from one region may sell for scarcely less than niggerheads, while those from 
another locality would not be looked upon with the thought of marketing. The species 
of Quadrula, asa rule, have more uniformity wherever found; some are better than others, 
but when a Quadrula is found there is a reasonable presumption that it is a shell of a 
certain grade, according to its species. 
The primary commercial difference between Quadrula and Lampsilis is that the 
latter rarely shows any marked iridescence. Sometimes iridescent qualities are referred 
to, but this generally means merely an unusually bright luster. On the other hand, 
Lampsilis mussels have a more uniform thickness, and therefore yield a larger number of 
blanks per ton than any of the Quadrulas. 
Some of these mussels are not surpassed in texture and luster, as will appear, and 
therefore this class of shells has been growing in favor in recent years. As previously 
mentioned, the raw materials first used in fresh-water button manufacture were species 
of Lampsilis. 
The Lampsilis mussels are more rapid of growth than the Quadrulus, and they are 
long-term breeders. In the latter part of the summer, as a rule, the marsupial pouches 
are filled with eggs which develop into glochidia, and in this condition all or a large 
proportion of them are held over the winter. Glochidia can be found in the gills of the 
females at almost any season of the year. July and August, principally, constitute the 
