12 



Mr. JAMES H. EMERTON made an interesting statement 

 of the results of his observations on the 



WORMS OF THE GENUS NAIS. 



He mentioned that, Oct. 21, he took from the large 

 pond near Legg's hill a quantity of bladderwort and 

 other floating plants, among which, with the animals usu- 

 ally found in the pond, were large numbers of worms of 

 the genus Nais, each wearing a tubular case covered with 

 seeds and water plants and in part with the eggs of 

 Daphnia. On removing the cases, a large proportion 

 of the worms showed the beginning of a division into 

 two and sometimes the struggles of the worm while its 

 case was being removed were enough to complete the 

 separation. 



The first appearance of division was a larger interval 

 than usual between two pairs of setse near the middle of 

 the body, around which a slight wrinkle marked the line 

 of future separation. 



Just behind this crease, on the under side of the body, 

 next appeared rudiments of four pairs of bunches of 

 hooked setae, marking the four segments next behind the 

 mouth of a new worm. At the same time in front of the 

 line of division appeared a great number of new segments 

 crowded together, which were to form the posterior eiid 

 of the forward worm, and just behind them grew out a 

 pair of long appendages, like those at the end of the old 

 worm. The line of division became more and more dis- 

 tinct, until the appearance was presented of one worm, 

 with another just like it fastened to its tail. At length 

 the division took place, and at the divided part one worm 

 developed a new mouth, and the other a new set of respi- 

 ratory appendages. 



In a few days another worm, Chsetogaster, appeared in 



