The Lake a7id Brook Lampreys of New York 45 i 



Whenever a larva swims it is always dorsal side up, 

 but in resting on the top of the sand or on the bottom of a 

 vessel of water it lies on the side. Apparently the side on 

 which it rests is a matter of chance as it is sometimes the left 

 and sometimes the right. 



Comparison of the I^arva with the Adult. — As one watches 

 the development of a lamprey's ovum it is seen that in a 

 very short time, 10 to 15 days, the embryo assumes characters 

 markedly like its parent ; but a closer study will show very 

 marked differences. Instead of a circular, sucking mouth 

 armed with teeth, the mouth is hooded and the entrance 

 guarded by a very perfect sieve (PI. VI, fig. 22), and between 

 the mouth and gills will be seen a reddish body that moves to 

 and fro rhythmically and in unison with the movements of the 

 branchial apparatus. 



If the branchial chamber is explored the seven branchial 

 openings on each side will not be found to open, each into a 

 separate sac or pouch, but into a large common chamber, a 

 chamber serving also for an oesophagus. The eyes, too al- 

 though visible do not reach the surface, but remain quite 

 deeply imbedded. Many other structural differences occur, 

 but a sufficient number have been named. In habits the dif- 

 ference is as striking as the difference of structure ; the parent 

 is a free-booter, the offspring lives an orderly and isolated life. 

 It is no wonder that naturalists and fishermen should have 

 agreed that they were different animals ; that they were dif- 

 ferent stages of the same animal probably did not enter their 

 minds. 



So strikingly unlike are frogs and their young, the tad- 

 poles, that it would be deemed almost incredible that one is 

 the offspring and would assume the appearance of its parent 

 if the facts were not forced upon every one that is at all ob- 

 servant. The transformations in insect life, too, are even 

 more marvelous, but from their frequency are taken as matters 

 of course. Apparently, a fisherman and naturalist of Strass- 

 burg Leonhart Boldner in 1666, knew of the metamorphosis 

 of the lampreys, and that the larvae were larvae and not dis- 

 tinct animals. But this was lost sight of, and the knowledge 



