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BULLETIN OF THE BUREAU OF FISHERIES. 
Tablb II.— Number op Larval P. donaciformis Carried by the Host. 
Species of fish. 
Date 
secured. 
Number 
of glo- 
chidia. 
locality. 
Aplodinotus grunniens 
Aug. 9, 1910 
Aug. 15,1912 
Aug. 16,1912 
1, 100 
300 
1*495 
I, 200 
76 
2 
280 
2.800 
1, 000 
1.800 
New Boston, III. 
Do. 
Do. 
Do. 
Do. 
Fairport, Iowa. 
Do. 
Do. 
Do. 
Do. 
Stizostedion canadense 
Aug. 15,1912 
Aug. 22, 1912 
Aug. 24,1912 
Oct. 30, 1912 
Nov. 9,1912 
Butterfly (Plagiola securis). 
But a single glochidium, well encysted, has been found by the writer, this being 
found on a sunfish {Apomotis cyanellus) taken July i , 1912 ; no development was indicated. 
Experiments in artificial infection of the black bass, crappie, sunfish, and catfish 
with this larva have proved unfavorable, so that we must conclude the specific host is 
as yet unknown. 
Bullhead, ShEEpnosE {Pleurobema cBsopa). 
A sauger {S. canadense) was taken July 20, 1911, holding 17 glochidia of this mussel. 
As the anterior and posterior adductor muscles were clearly defined and the foot more or 
less conspicuous, indications are that this fish is at least an occasional host of this larva. 
As the mussel itself is not at all common, the sauger may eventually prove to be the 
specific host. An infection is shown in figure 17. 
NiggERHEad {Quadrula ebena) . 
The discovery of the specific host of this mussel on August 13, 1912, was a great 
gratification, occurring as it did after almost three years’ experimentation. Repeated 
failures in obtaining artificial infections with all the species of fish obtainable in the 
vicinity of Fairport led me to search for fish not previously taken, of which the skipjack 
(P. chrysochloris) was about the only one remaining. The taking of a specimen of this fish, 
June 18, 1910, by H. Walton Clark, was overlooked till after the August, 1912, 
material was identified, when his note was looked up and later the fish itself secured and 
found to be heavily infected. Mr. Clark, while recognizing at the time of taking that his 
1910 specimen was carrying glochidia in great numbers, was unable to identify the 
species of mussel owing to lack of material, no glochidia of Q. ebena being available at 
that time for comparison. Owing to the great commercial value of this shell, which is 
exceeded by none, the final discovery of the host is of far-reaching importance. 
During the season of 1912, 15 specimens of Pomolobus were secured in the vicinity 
of Fairport and New Boston, the 5 specimens secured during August all bearing glochidia 
in large numbers, ranging from 1,895 to 3,740 for each fish. During this month little 
development of the glochidia was shown which would indicate recent infection, but a 
