1851.] 321 



PLUMATELLA, Lamarck. 



1. Pltimatella diffusa, Leidy. Pr. A. N. S., V. 261. 



2. Pl.UMATELLA NITIDA, LeUlj/. 



More robust than the preceding, color light olivaceous brown, consisting 

 usually of only a few branches ; tubes amphoraeform, without a keel, smooth or 

 transversely corrugated near the orifices which are entire. Length of the 

 articuli one line, breadth one-fourth of a line. Polyp has the same form as in 

 the preceding, and also the same number of tentaculag. 



Hubilution. Found with the preceding. 



Remarks in connection iuith Plumalella. Almost every stone, in many parts 

 of the Schuylkill river, particularly below the dam at Fairmount, has adher- 

 ing to it numerous eggs of Plumatella in short rows, which upon superficial in- 

 spection resemble prismatic crystals of some mineral. 



PALUDICELLA, Gerv%is. 



1. Paludicella elongataj Leidy. 



Coenaciuin attached throughout, or attached by only a (e\v articulations, the 

 remainder floating; delicate, very much branching, colorless or ambreous, 

 shining. Articulations very long, claviform ; tubes of exit variable in length, 

 placed close to the distal extremities ; orifices entire, 



Poli/ps with sixteen tentaculas arranged ia the form of an inverted cone. 

 Stomach brown in color. 



Mcusurernent.s. Articuli of ctEncecium to I line in length, by 1.133d in. in 

 breadth at the dilated part, and l-28.5th in. at the narrow part. 



Habitation, On the under side of stones in the Delaware and Schuylkill 

 rivers. It is found in vast profusion below the dam of the Schuylkill at 

 Philadelphia. 



Besides the foregoing, I have observed what I suspect to be the ccenoecium of 

 a new genus of Polyzoa, although I have never been able to detect the polyps if 

 such exist. It resembles when viewed by the naked eye a very minute Isis 

 hippuris, or the corraline Amphiroa corymbosa. Under the impression that it 

 belongs to the Polyzoa, it may be characterized as follows. 



URNATELLA, Leidy. 



Ccencccium membrano-corneous, consisting of several divergent, unbranching 

 filaments, attached by a common basis. Filaments consisting of a series of urn- 

 shaped articulations, with a solid axis passing through the whole, and having 

 to each articulation one, occasionally two, tubes of exit with the orifices expand 

 ed, placed inferiorly near their commencement. 



Urjjatella gracilts, Leidy. 



Usually three to five filaments arising from a common basis of attachment. 

 Articulations up to nine in number to a filament, very regularly nrnform except 

 the distal two which are inverted pyriform, decreasing in breadth from the first 

 to the last. Body portion of each urnform articulation yellowish white, trans- 

 lucent, with fine transverse bands or stricp, and punctae of brown ; neck or pe- 

 diculate portion, columnar, transversely contorted, expanded at base, black. 

 Tubes of exit one, occasionally two, to each articulation except the last, which 

 has none, placed at the lower part of the body portion of the articulation, and 



