FRESH-WATER MUSSELS AND MUSSEIv 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 hoykiniana 

 (Lea). 



The bank climber, Qtcadrula trapezoides (Lea) (PI. 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 is a very familiar shell in Louisiana, Arkansas, and eastern Texas. 



The buck-horn, Tritogonia tuberculata (Barnes) (PI. 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, as a 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 

 110306°— 19 2 



