UUNA 
tella gracilis, a fresh -water folyzoax. 
I seen any published notice of its having been discovered by other observers.^ In o,u 
instance, n.v friend Dr. Isaac Lea directed my attention to tlm shell ol a Ln^o, from 
the Scioto River, Ohio, on whicli were several dried, but stdl charactenstic, specimens 
of Urnatella. This fact not only indicates the existence of the polyp m the lallei eif 
the Mississippi, but probably also a wide distribution of it throughout the country. 
From the time I first saw Urnatella I felt it was of such interest as to be wortliy 
of a thorough investigation, and this I resolved to undertake at a favorable oppor- 
tunity. Otlier occupations, and the want of a ready supply of the neces.sary material, 
liave prevented my intention, and I am now led to communicate what I have learned 
of the animal, with the view that some of my younger countrymen and co-laborers, 
under more fevorable circumstances, may be induced to do what I had liojied and 
wished to do. 
Urnatella is a most beautiful form, and quite peculiar among tlie known fresli- 
wat 3 r polyzoa. In its relations it is most nearly allied to the marine genus Pedkellina, 
typical of a small order of the polyzoa, and of the family Pedicellime. 
Urnatella lives in positions and has habits similar to those of the iamiliar Pluma- 
tella, species of which are found almost everywliere in fresh waters, from tlie little 
rivulet to the largest lake. It is attached to fixed objects, commonly the under side 
of stones, beneath which the water freely flows. In this manner it was rejieatedly 
collected on stones, taken from the bed of the Schuylkill R,i\er, in association with 
Plnmatella vexiev laris, Paludicella elmujata, Linmias sccialis. Hydra earnea, Sjxynyilla 
fragilis, and several worms, such as Plauariu, Kmea ruhra, Clejisine, Manayiiid.-ia 
sjieriosa, etc. In the same locality, in a few instances, I found it attached to shells ol’ 
Unin eonvplanatns and Melania viryinica ; and less frequentlv young spi'cimens were 
observed on eel-grass, Vallisneria spiralis, and on Avater-star-grass, Scholhra yraminea. 
Recently Mr. Edward Potts .submitted to me several specimens taken from a pu'ci' 
of sunken wood from the c-anal at Fairmount. 
As more commonly observed, Urnatella consists of a pair of stems pendant from 
a common disk of attachment and terminating each in a single polyii-head or bell, or 
in several little branches terminating in like manner, as seen in figures 1, 2, Plate 1. 
The stems diverge, straight or in a gentle curve, are slightlv tapering, beaded in 
appearance, alternately whitish or brownish Avhite and black. U.sually they are com- 
posed of from two to a dozen segments, including the terminal polvp-bcdl and reach 
from an oighth to „ sixth of an inoh in length. The largest s,,eein,ens oheerv,.d 
consisted of eiglit™, .segments, ,vith a length of about the fonrtl, of an inch Tlie 
Waded a,,, lean, nee of the ,,oly|.-ste,ns is due to the expansion with light coloring „f 
the median portion of the segments, and the intermediate nariwing I'lnd hlack folor 
ill rrrrT The stems may end alone in a single 
po p-bell I, nt commonly in addition they have one or tivo pairs of lateral hninclu-s 
rvith terminal bells, coming off fom the two segments of tl e main stem nex "o t 
