30 BULLETIN OF THE BUREAU OF FISHERIES. 
from 100 pounds of Lake Pepin muckets. This shell is, therefore, the nearest approach 
to an ideal button shell now found among fresh-water mussels. 
The rate of growth is relatively rapid. At the Fairport station mussels of this 
species have grown to a length of more than 1 inch within six months after the date 
of infection upon the fish. These were in floating crates in the river. The age of com- 
mercial shells can not yet be positively stated but it is probably from 4 to 6 years.% 
Like most others of the genus, it is a long-term breeder. Its fish hosts are the common 
game fishes, such as the basses, crappies, stnfishes, perches, and sand pikes. Some 
have been grown in ponds at the Fairport station to a length of about 1 inch in a season, 
and very thin buttons have been cut from such shells at the end of the second growing 
season. The Lake Pepin mucket lends itself to methods of artificial propagation better 
than any other species. 
Lampsilis hydiana (Lea) may be called the southern fat mucket, being found in 
the lower portion of the Mississippi Basin. The specimens we have had might easily be 
confused with the Lake Pepin form and appear to resemble it in qualities of shell. It 
occurs in Louisiana, Texas, Arkansas, and neighboring States. 
The butterfly, Plagiola securis (Lea) (Pl. XV), presents another case of a mussel 
which must be placed far from its systematic position. Its shell qualities place it more 
nearly with the muckets than with any others. It is a well-known mussel of the larger 
streams of the Mississippi and Ohio drainages and is reported from Alabama. Its 
beautiful form and markings give it the name of butterfly. Mr. Boepple remarked that 
comparatively few females were found, and that they are of much lower commercial 
value than the males, on account of being so much thicker and lacking in luster. 
The shells of the males are very flat and have a white color and good luster, with a 
rather uniform thickness over most of the shell. There are few places where 100 pounds 
can be obtained, but they are often met with in mixed shipments, and are valued. 
It is a long-term breeder, and its most common fish host is the fresh-water drum, or 
sheepshead, A plodinotus grunniens. 
A smaller species, the deer-toe, Plagiola elegans (Lea), is very common, but rarely 
attains a size sufficient for cutting blanks. 
POCKETBOOK GROUP. 
The pocketbook, Lampsilis ventricosa (Barnes) (Pls. XV and XVI), is a large and 
very inflated mussel found throughout the Mississippi and Great Lakes drainages 
(as well as in the Nelson River), in large and small rivers, and in some lakes. It is one 
of the species most familiar to the fishermen and most readily obtained. It is found in 
gravel bars or sandy bottom, sometimes alongshore and sometimes in the deeper water. 
The commercial value of the pocketbook is generally rather low. The shells of the 
male are better than those of the female. There are some rivers in which the pocket- 
book becomes a very good shell for button manufacture. Mr. Boepple had an example 
from the Yellow River of Indiana, from one side of which 52 18-line blanks were obtained, 
all of which would make good buttons. The Yellow River specimens are among the best, 
since the hinder or tip portion of the shell is thick enough for buttons. As a rule 
better shells are found in small rivers and creeks than in the large rivers. 
a At ages of 314 and 4}4 years some Lake Pepin muckets reared in a pond at the Fairport station yielded ra to 22 14-line 
blanks over 234 lines in thickness. 
