PROCEEDINGS 



OF THE 



Delaware County Institute of Science 



Vol. Ill, No. 3 April, 1908 



MICROHYDRA during 1907. 



BY EDWARD POTTS. 



Observations during the year 1907 directed toward the 

 determination of the obvious life history of the most recently 

 discovered and least familiar species of North American Fresh 

 Water Hydroids, Microhydra rvdcri \ — recently discovered, 

 although it was found twenty-four years ago ; least familiar ; 

 for, excepting Dr. John A. Ryder, no competent scientist, 

 within the knowledge of the present writer, has collected or 

 described it. 



FIRST NOTICE. 



At the date of the preparation of his first and only pub- 

 lished article {American Nahwalist, Extra, December, 1885, 

 page 1232) Dr. Ryder had not seen the living Mic?vhydra 

 ryderi. Later, a full stock was placed in his hands and care- 

 fully studied ; resulting in the preparation of several valuable 

 drawings, many of which have been used in illustration of 

 other articles ; but his lamented death prevented the prepara- 

 tion of such a history and description as the novelty of the 

 animal seems to demand. His only textual reference to Micro- 

 hydra now in my possession forms part of a lecture upon some 

 abstruse subject and says : " The lowest and simplest hydroid 

 yet discovered, the Mlcrohv.lra ryderi, I'otls, may throw some 



LiBK,' 



