FRESH -WATER POLYZOA. 237 



separation and settlement elsewhere, become the foun- 

 dation of new colonies." 



Thus far I have not been fortunate enough to find a 

 specimen of Urnatella, although it is probably not rare 

 among stones in running water. A sight of its beau- 

 tiful and curious collection of urns tipped by its grace- 

 ful bell and swaying tentacles is worth many a long 

 tramp, and careful scrutiny of many a wet stone. My 

 account of this Polyzoon, because of my want of ac- 

 quaintanceship with it, is gleaned from a paper, already 

 referred to, by Dr. Leidy, who discovered and named it 

 Urnatella grdcilis. 



And those who desire to be fully informed as to the 

 anatomy of the charming creatures which form the 

 group of the fresh- water Polyzoa, and to distinguish the 

 several species, are referred to Professor Alpheus Hy- 

 att's work on " The Polyzoa," published by the Essex 

 Institute, Salem, Mass., and to Professor Joseph Leidy's 

 papers on the subject in the Journal of the Academy 

 of Natural Sciences of Philadelphia. 



