CONCERNING POTTSIELLA ERECT A. 



As interesting items in the history of this polyp, we reprint 

 the following from the Proceedings of the Academy of Nat- 

 ural Sciences, Philadelphia, with subjoined notes from Mr. 

 Edward Potts : — 



August 5th, 1884. Mr. Edward Potts in the chair. 



On Paludicella erecta. — Mr. Edward Potts desired to have 

 a preliminary record made of his recent discovery or identifi- 

 cation of a new species of Paludicella, for which he proposes 

 the name Paludicella erecta. 



This genus of fresh-water polyps has heretofore contained 

 only the single clearly defined species P. Ehrenbergi, Van 

 Beneden {Alcyonella articulata, Ehrenberg), the other two 

 names, P. procumbens and P. cloiigata, suggested by Mr. 

 Albany Hancock and Prof. Leidy, being considered by Prof. 

 Allman as identical with the original type. The present form 

 is strikingly different from the old one, both in the number of 

 its ciliated tentacles and in the character of the ccenoecial 

 cells. The doubt which has lingered in the mind of the 

 speaker has not been as to the species, but whether, in view 

 of the difficult determination of the characteristic septse 

 between the cells, amounting in fact to an apparent absence 

 of them, a new genus might not be required to accommodate it. 



It was first noticed in Tacony Creek, a small stream in 

 Montgomery County, Pennsylvania, at that place perhaps 

 fifty feet above tide-water. A few days after it was also gath- 

 ered within tidal limits in both the Delaware and Schuylkill 

 Rivers, near Philadelphia. In the first-named locality it was 

 found most abundantly in the pools amongst the rapids of the 

 stream, frequently covering the upper surface of stones, at 

 the depth of a foot or more, to the extent of many square 

 inches. The erect portions of the ccenoecial cells in the 

 denser parts of the colonies are about a line in height and, 

 standing very closely, suggest a comparison with the surface 



