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of a stone of the size of a hen's egg, at the top of the fall, in- 

 creased in size just in proportion to the increasing distance of the 

 vibrations, retaining its circular foi'ra, and finally expanded to 

 fourteen inches in diameter. Upon the top of the dam they could 

 see distinctly through the current to the edge of the timber over 

 which the water breaks, and they found that the water at this 

 point acquires a tremulous motion, giving origin to the ridges or 

 vibrations alluded to above, which here follow each other at in- 

 tervals not exceeding one quarter of an inch. The sheet of water 

 at the top of the dam is six inches in thickness ; at the bottom 

 two and a half inches. The ridges are evident on the inside the 

 whole length of the fall, but upon the outside they do not make 

 their appearance for the space of ten or twelve inches. They in- 

 crease in size relatively with the distance. 



Mr. John Green presented several specimens of Fishes 

 from Surinam. They were the female Anableps Gronovii, 

 with the ovary containing the young exposed to view ; 

 the Aspredo levis, with its eggs adherent to its abdomen ; 

 and a species of Bagre which carries its eggs in its 

 mouth, some of the young fish being seen just hatched 

 from the egg. The eggs in this specimen chanced to be 

 of two distinct species, showing that the fish may get 

 and carry in its mouth the eggs of another. He knew 

 of six species which carry the eggs in the mouth. 



The President said he had examined several specimens of 

 Bagre before finding one with the eggs of a diiferent species in 

 its mouth. The young are found alive, either within the envel- 

 opes of the eggs or already hatched, even when the fish has 

 been dead some length of time. The number of eggs in the 

 ovaries is small, not greater than can be carried in the mouth, 

 and are in three different stages of development, so that they are 

 not all discharged at the same time. 



Dr. Charles Pickering alluded to the indestructible nature of 

 the eggs of some fish ; they have been known to hatch after 

 traversing the intestinal canal of a bird. 



Dr. A. A. Gould observed, that at a recent meeting of the 



