The Lake and Brook Lampreys of N'ew York 443 



the lampreys making them. The central part is usually 15 to 

 20 centimeters deeper than at the edges so that the whole is 

 nest like or dish-like in appearance. At the lower edge is 

 always a pile of stones which were carried down in making 

 the nest. As the stones from the upper edge and sides of the 

 nest are loosened the sand is carried down by the stream and 

 lodges in the deepest part of the nest. After the nest has a 

 considerable pile of stones at the lower edge and a good layer 

 of sand in the bottom it is ready to receive the eggs. In 

 ovulation the female secures herself firmly to a large stone at 

 the side or upper edge of the nest so that the body can extend 

 out into the nest, then the male fastens to the female, some- 

 where near the head, he then winds him.self halfway around 

 the female, whereupon the two bend their tails downward and 

 stir up the sand by the most vigorous movements. Simul- 

 taneously the ova and the milt are forced out in a stream and 

 mingle in the water, and also mingle with the sand. The 

 eggs are coated with an adhesive substance which enables 

 them to adhere to any solid they come in contact with, con- 

 sequently they stick to the particles of sand that have been 

 stirred up in the water and, as the eggs are themselves heavier 

 than water and made still more so by the particles of sand to 

 which they adhere, they quickly sink to the bottom before the 

 current can carry them below the nest ; they are also partly 

 covered by the depositing sand. If many eggs have been ex- 

 truded, all are not covered and the bottom of the nest may be 

 quite thickly strewn with them. In nearly all cases some re- 

 main uncovered. After the pair have " shaken together" as 

 the ovulation is called, they separate and commence at once to 

 remove stones from the upper edge and sides of the nest and 

 pull them down stream as if to enlarge the pile at the lower 

 edge. This was at first puzzling, for the nest is apparently 

 completed before the ovulation begins. The explanation soon 

 became evident, for while immediately after "shaking to- 

 gether" there might be many uncovered eggs, in a very short 

 time they all disappeared, being covered by the sand that was 

 loosened by the removal of the stones and carried down the 

 stream bv the current. 



