2 BULLETIN OF THE 
first published drawing of the calyx and young branches. Allman was 
inclined to refer this genus to the Pedicellinide. 
In 1870 Leidy recorded further observations on Urnatella, and in 1884 
he published in a thin quarto, with a single plate, everything which he 
had found out about its anatomy and physiology. The main points of 
these papers will be brought out in connection with the organs to which 
they refer. 
Finally, Mr. Edward Potts, in a note to one of the editors of the 
American Naturalist (April, 1891), states that he has succeeded [as did 
Leidy] in obtaining in the spring rejuvenated heads from the headless 
stems of Urnatella gathered the preceding fall. 
Various writers have called attention to the imperfections in our 
knowledge of this aberrant form. Ehlers (’90) has made many sugges- 
tions concerning the anatomy of Urnatella, which, being purely hypo- 
thetical, require to be settled by observation. Leidy himself was impressed 
with the importance of a better knowledge, and he had intended, he says 
(84, p. 6), to make a thorough investigation of it. ‘‘ Other occupations, 
and the want of a ready supply of the necessary material, have 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 favorable circumstances, may be induced to do 
what I had hoped and wished to do.” To supplement the work of Pro- 
fessor Leidy is the object of the present paper, which has been largely 
inspired by his. 
In 1884 Leidy remarked upon the absence of Urnatella from its former 
haunts. Apparently nothing had been seen of it since that time, until, in 
1889, I opened correspondence with Mr. Edward Potts of Philadelphia 
upon the subject. In the summer of 1890 Mr. Potts and I thoroughly 
examined the waters of the Schuylkill River, both above and below the 
Fairmount dam, but without finding any trace of Urnatella. In Septem- 
ber, 1891, Mr. Potts found many stocks in the bed of the temporarily 
emptied Schuylkill Canal, below Flat Rock dam, and kindly forwarded 
some of these, living, to me at Cambridge. In July, 1892, Mr. Potts 
and I re-examined in vain the Schuylkill River at Fairmount dam, and 
finally, on July 4, made dredgings in the Schuylkill at Flat Rock dam, 
near Shawmont Station, Pennsylvania. We found no trace of Urnatella 
in the quiet waters above the dam, but in the turbulent waters im- 
mediately below the overflow almost every stone brought from the bot- 
tom bore stocks, and some were almost completely covered on one face 
with luxuriant growths. One barrel-hoop dredged from the mud was 
