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BULLETIN OF THE BUREAU OF FISHERIES 
of them, about the size of a hickory nut, was said by the fishermen to be found on 
one smelt. Some of these were saved and identified by Prof. J. Percy Moore, of the 
University' of Pennsylvania, as Piscicola milneri. It is not evident that they are 
harmful to the smelt. 
Henry B. Ward, who studied the internal parasites of Sebago salmon in 1906, 
mentions but one internal parasite of the smelt. In the salmon he found a new tre- 
matode, which he named Azygia sebago, and it was the only trematode found in the 
salmon. In order to ascertain if the smelt played any part in the life history of this 
distome, he examined 52 smelts, and in 46 of them he found specimens of Azygia 
sebago. He said: 
The parasite occurred in the stomach only and the infestation was small, from 1 to 14 distomes 
being found in each host, with an average of only four to a fish. In most cases the parasites which 
were taken from the stomach of the smelt were immature, not having yet reached that size at which 
the production of ova begins; they were on the average 3 to 4 mm. long, or in some cases even 
smaller, running from 1.5 to 2.5 mm. [less than ^ inch] in length. Single specimens reached a 
length of 6, 7, and even 10 mm. [nearly inch]. In one case, indeed, there was none shorter than 6 
mm., and the specimens varied from that to 10 mm., so that one can not fairly maintain that they 
never reach the size attained in the salmon. Nevertheless, after the account is cast up the average 
shows distinctly that the distomes do not reach their full size in the smelt and, so far as collections 
made during July and August can indicate, those taken from this host are usually small in size and 
sexually immature. I did not obtain any information as to the source from which the smelt acquires 
infection, but in view of the universality with which smelt form the food of the salmon in Sebago 
Lake the latter undoubtedly owe to them the major portion of their infestation with this parasite. 
In a footnote Ward states that these distomes occurred equally in both sorts of 
smelt and those from the smaller smelt were larger than those from the larger fish. 
“This,” he said, “is, of course, a mere accident, but it serves to show that the two 
types of smelt conduct themselves alike toward the parasite. ” 
Professor Doolittle found some smelts from Sunapee Lake with the alimentary 
tract containing parasitic worms, such as tapeworms, distomes, and threadworms. 
Subsequent examination by D. R. Crawford, of the Bureau of Fisheries, of 94 speci- 
mens from nearly l 7 /g to about 4^g inches long revealed that 27 were more or less 
infested by cysts of some parasitic worm in the walls of the stomach, and one was 
heavily parasitized, having cysts in the liver as well as in the stomach. Each of 
two specimens contained a small worm. The 29 parasitized smelts ranged from about 
2 Y 2 to a little over 4^ inches, averaging nearly 3 inches. Ninety-four specimens 
were found dead and dying along the beach at Soo-Nipi Park on April 22 and 23 
and November 8, 1910. Parasitized fish were found in both April and November. 
Of 71 smelts from about 4 inches to nearly 5.3 inches long, from Massabessic Lake, 
N. H., on April 14, 1904, 34 were infested with cysts in the stomach, the majority 
heavily so. These were all spawning fish and had no food in their stomachs. 
As previously remarked, it is not known how harmful or harmless the parasites 
mentioned (or any other parasite) are to the smelt. As Doctor Wilson said, the 
copepod parasite is a menace only when conditions for its undue increase or other con- 
ditions are very favorable. He mentions that certain small fishes, by eating the 
parasite while in its free-swimming stage, ordinarily keep it within due bounds; but 
such fishes as darters and top minnows, which he mentions, do not occur in Sebago 
