212 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



are sufficiently developed they metamorphose into adults, find their way down the 

 inlet into the lake, and begin the same kind of parasitic bloodsucking life that their 

 parents led. Thus is the cycle of life completed for these creatures. 



In structure and zoologic position the lampreys are the lowest vertebrates found 

 in this region, being placed at the very foot of the list of fishes and by most recent 

 authors they are even denied admission into the class of fishes. The class to which 

 they belong is Marsipobranchii, or "pouch gill," because the gills form a series of 

 pouches, seven on each side of the head. They receive their water through as many 

 independent gill-openings. 



The adult lamprey swims in the water like a fish, only with more of a wriggling 

 or snake-like movement, but it does not have paired fins placed as in the true fishes. 

 The only organs that it has that functionate as fins are membranous expansions on 

 its back and on the dorsal and ventral sides of its tail. 



As will be seen from the figure of the mouth (p. 211), it has no jaws, but its mouth 

 is a large circular disk, thickly studded with large, strong, chitiuous spines or teeth, 

 which enable it to more securely grasp its victim. This disk is surrounded by a softer 

 membrane, which readily fits tightly over any surface and makes it possible for the 

 animal to adhere quite firmly to an object by suction when the piston-like tongue in 

 the center is drawn back. Having fastened itself by this wonderful mouth, which is 

 larger around than its head, it rasps away with the saw-like teeth on its tongue, using 

 nearly 150 other teeth, until it has worn through the thick skin or scales of its victim. 

 Then it has nothing to do but to remain attached to the fish and be carried around by 

 it, sucking blood when it is hungry, and occasionally rasping away at its raw flesh, 

 making the hole deeper and deeper until finally the abdominal wall is completely 

 perforated and the body cavity penetrated. Often the intestines or other organs of 

 the fish are attacked and cut to pieces, but more frequently the lamprey fastens itself 

 at another place if its victim has any blood left, or if not it seeks another lish. 



The intestines protruding and the blood escaping from the deserted wound, in a 

 great many cases sooner or later cause the death of the fish, which are often seen 

 swimming in the lake in the miserable condition just described. The injured fish does 

 not always die, but in every case it is seriously weakened and reduced in flesh, and 

 blood, and in the power of fully reproducing its kind. Among some specimens 

 recently collected for study here was a bullhead or horned-pout (Ameiurus nebulosus) 

 tli at had been so severely attacked by a lamprey that its stomach protruded through 

 the hole in the side. This fish was kept alive in a tank (for the purpose of observing 

 its condition) for three weeks. 



Last spring (1897), when using a collecting seine under the permission and direction 

 of the New York Fisheries, Game, and Forest Commission, the writer found by actual 

 experiment that it was easy to distinguish the bullheads that had been attacked by 

 lampreys, even when they were purposely turned over so that the holes were not visible. 

 The injured fish loses entirely its rich golden hue, and, assuming a sickly appearance, 

 grows paler and weaker. It is not at all uncommon to find dead fish along the 

 shores of Cayuga Lake, and upon examination the marks of the lamprey may be seen. 

 Among such fish recently found are the bullhead or catfish (Ameiurus nebuliwHx), 

 suckers (Catostomm), carp (Cyprinu* carpto), lake herring (Aryyrosomus artedi), and 

 pickerel (Lucius reticulatu*\ Other species of food-fish are also injured. It is a 

 serious enemy of the sturgeon (Acipenser rubicundus), one of which was caught in 



