NATURAL HOSTS OF FRESH- WATER MUSSELS. 
II3 
Pimple-back {Quadrula pustulata). 
But two glochidia of this species have so far been detected and this on a crappie 
(P. annularis) taken September 12, 1912. While it is rather late in the season to expect 
to find this mussel still parasitic, it is not believed that the identification is wrong, yet 
the development should have progressed more rapidly than is the case in this instance. 
Pimple-back {Quadrula pustulosa). 
October seems extremely late to find any Ouadrulas persisting, but the gills of a 
crappie taken the 17th of that month reveals a single glochidium of what I am com- 
pelled to regard as this species. No development whatever is indicated and the pres- 
ence of the glochidium at this late season may be due to some freak physiological 
characteristic not easily understood. 
Quadrula solida. 
Two sunfish {Lepomis pallidtis) were taken July i, 1912, bearing glochidia of this 
mussel, one having 50 present, the other only 6. The development is similar to that 
noted in plicata, the foot and adductors being clearly indicated. The shell itself is not 
at all common in this region, and one would naturally expect to find few fish infected. 
The glochidium of this species closely resembles that of ebena and might be mistaken 
for the latter by a careless observer, but may be recognized by its greater comparative 
depth and shorter, straighter hinge line. 
Pig -TOE {Quadrula trigona). 
From the frequency with which this shell is found in the vicinity of Fairport, it is 
surprising more infected fish are not taken, its spawning season being July and August. 
So far only a single black crappie {Pomoxis sparoides) taken June 25, 1912, has been 
found infected, and it held but three glochidia, none of which showed any development 
whatever, thus indicating recent infection. 
SUMMARY. 
In conclusion attention is directed to the table of fish examined (table v), following. 
The remarkably small percentage of fish infected in a state of nature will be apparent 
at once, even of those species known to carry glochidia, if we except the skipjack 
{Pomolobus chrysochlaris) . In the case of the sheepshead, known to be the specific host 
for two species of mussels, the percentage is about 3^, while in Pomoxis annularis, which 
carries more species of mussels than any other fish, it is only seven-tenths of i per cent. 
Out of a total of 38 species examined, numbering some 2,815 individuals, only 46 fish were 
infected, but of course only ii species are apparently susceptible to natural infection. 
Further investigations will reveal much, the work having only begun. A summary of 
the present known hosts is shown in table vi. 
