2 BULLETIN OF THE 



first published drawing of the calyx and young branches. Allmau was 

 inclined to refer this genus to the PedicellinidiB. 



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 watei'S 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 



