REPORT OX THE FRESH-WATER BRYOZOA OF THE 

 UNITED STATES." 



B}' CiiARLKs B. Davknport, 



AsHoi-iiilt' f'mfi-sxor of Zoologn, JWiversity of Chicago. 



The fiH'sh-water Fryozou do not constitute ;i naturiil oroup of 

 aniiuiils. hut have di^sccnded from ancestors Ix'longini;" to widely dis- 

 tinct families. There can ])e no question that these ancestors were 

 marine animals. Excepting the subordcM- Fhjdactohvmata. all fresh- 

 water Br3^ozoa belong- to groups most of whose representatives are 

 marine. The fresh-water forms seem to have made their way up 

 estuaries and rivers to lakes and ponds. Here they acquired the 

 capacity of forming statoblasts or hil)ernacula. ])y virtue of which the 

 species was enal)led, on the one hand, to survive the winter and, on 

 the other, to be carried by waterfowl and winds over divides from one 

 drainage basin to another. Thus the fresh-water species have liecome 

 nearly cosmopolitan. PJainatdJa jyrhiccps has l)een found in North 

 and South America, throughout Europe, in Molucca, Japan, and 

 Australia — i. e., in all but one of the great geographical di\ isions of 

 the land areas of the glohe. The localities given in the following list 

 do not at all represent the true area of distribution of fresh-water 

 Bryozoa in Noiih America, hut oidy the regions wliere the inhab- 

 itants of the waters h;ive been carefulh' studied. These regions are 

 for the most part eastei-n ]\Iaine (Hyatt); eastern Massachusetts 

 (Hyatt and the writer); southeastern New York, especially Cold Spring 

 Harbor, Long Island (the writer); vicinity of Fliiladclphia and Balti- 

 more (Leidy, Potts, and Hyatt); lakes Eric and Michigan (Reighard. 

 Ward, Forl)es. Landaere, and the writer); Illinois lakes and rivers 

 (Forbes and H. (iarnian); Yellowstone National Park (Forbes). It is 



«This paper is based chiefly on materials collected during 1898 aad 1899 by the 

 laboratory of the U. S. Fisli C'oininission, located at Put in Bay, Oliio, and under the 

 direction of Prof. .Tacob Reighard; by tlie IlUnois State Laboratory of Natural His- 

 tory, Prof. S. A. Forbes, director; and by the writer in the Ea.stern and Middle 

 States. It was made at the re(|uest of Professor Reighard anil all recorded data on 

 the distribution of American fresh-water Bryozoa have been consulted in its 

 preparation. 



Proceedings U. S. National Museum, Vol. XXVII— Nu. 1355. 



