1884.] natural sciences of philadelphia. 213 



August 5. 

 Mr. Edw. Potts in the chair. 

 Eleven persons present. 



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

 preliminary record made of his recent discovery or identification 

 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. Ehrenhergi^ Van Beneden 

 (Alcyonella articulata, Ehrenberg"), the other two names, P. pro- 

 cumbens and P. elongata, suggested by Mr. Albany Hancock and 

 Prof. Leidy, being considered by Prof. Allman as identical with 

 the original type. The present form is strikingly diff"erent from 

 the old one, both in the number of its ciliated tentacles and in 

 the character of the coenoecial cells. The doubt which has lin- 

 gered in the mind of the speaker has not been as to the species, 

 but whether, in view of the difficult determination of the char- 

 acteristic septae 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 Tacon}^ Creek, a small stream in Mont- 

 gomery County, Pennsylvania, at that place perhaps fifty feet 

 above tide-water. A few days after it was also gathered 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, fre- 

 quently 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 coenoecial cells in the denser parts of the colonies 

 are about a line in height and, standing very closely, suggest a 

 comparison with the surface of a chestnut-burr. In the rivers 

 they were found penetrating the mass of encrusting sponges, 

 particularly Meyenia Leidyi. 



These upright tubules are chitinous prolongations of very 

 irregularly inflated cells, resting in compact disorder upon the 

 supporting surface, crossed and connected in some manner not 

 yet intelligible, by meandering cylindrical rhizomes, sometimes of 

 great relative length. These are mostly terminal and simple, but 

 are sometimes branched and frequently originate in an indif- 

 ferent lateral portion of a cell. The tubular prolongations 

 are, of course, always single ; the invaginated polyp retiring 

 within the inflated portion of the cell. Septae were, in a few 

 instances, discovered in the rhizomes near their insertion or 

 connection with the inflated portion of the cells. The upright 



