72 NAIDES. 



twenty obsoletely defined segments, the two first twice as long as 

 broad, the others not so long as their diameter : mouth wide : bristles 

 twelve underneath the first segment, in the other segments there 

 are eight of lesser size. 



I have implicitly followed Oersted in his arrangement and defini- 

 tion of the Naides, for I have not been fortunate enough to meet 

 with a single species. 



