The Cyclostomes, or Lampreys 493 



up and down from the ventral toward the dorsal side of the 

 mouth. Around the mouth is a circle of soft membrane finally 

 surrounded by a margin of fimbria; or small fringe. This com- 

 pletes the apparatus with which the lamprey attaches itself 

 to its victims, takes its food, carries stones, builds and tears 

 down its nest, seizes its mate, holds itself in position in a strong 

 current, and climbs over falls. 



Mischief Done by Lampreys. — " The most common economic 

 feature in the entire life history of these animals is their feeding 

 habits in this (spaw .nig) stage, their food now consisting wholly 

 of the blood (and fieshj of fishes. A lamprey is able to strike 

 its suctorial mouth against a fish, and in an instant becomes so 

 firmly attached that it is very rarely indeed that the efforts of 

 the fish will avail to rid itself of its persecutor. AVhen a 1am- 

 prev attaches itself to a person's hand in the aquarium, it can 

 only be freed by lifting it from the water. As a rule it will drop 

 the instant it is exposed to the open air, although often it will 

 remain attached for some time even in the open air, or may 

 attach itself to an object while out of water. 



" Nearly all lampreys that are attached to fish when they 

 are caught in nets will escape through the meshes of the nets, 

 but some are occasionally brought ashore and may hang on 

 to their victim with bulldog pertinacity. 



"The fishes that are mostly attacked are of the soft -rayed 

 species, having cycloid scales, the spiny-rayed species with 

 ctenoid scales being most nearly immune from their attacks. 

 We think there may be three reasons for this: ist, the fishes 

 of the latter group are generally more alert and more active 

 than those of the former, and may be able more readily to dart 

 away from such enemies ; 2d, their scales are thicker and stronger 

 and appear to be more firmly imbedded in the skin, consequently, 

 it is more difficult for the lampreys to hold on and cut through 

 the heavier coat-of-mail to obtain the blood of the victim; 

 3d, since the fishes of the second group are wholly carnivorous 

 and in fact almost exclusively fish-eating when adult, in every 

 body of water they are mor.e rare than those of the first group, 

 which are more nearly omnivorous. Accorrling to the laws 

 and requirements of nature the fishes of the first group must 

 be more abundant, as they become the food for those of the 



