136 Roosevelt JVild Life Bulletin 



such cases the bacterial decomposition of the algae will not require so 

 much oxygen. If the treatment is made at a time when the waters 

 are not well aerated by the action of waves only a portion of the 

 lake should be treated at a time. Under this method there are regions 

 into which the fish may migrate and not be affected by the reduction 

 of the oxygen. 



In conclusion it should be pointed out that the killing of the algae 

 destroys an important source of food for fish. In general, algae are 

 not directly a source of food for many species of fish, although Tif- 

 fany ('aia, 2ib, '22) has shown that the young gizzard shad (Dor- 

 soma cepedianum) feed almost exclusively upon algae. Algae are, 

 however, the food of the aquatic animals upon which many fish feed, 

 and the complete removal involves the removal of their food supply 

 also (Transeau, '17; ]\Ioore, '20; ]\Iann, '21). It is very evident that 

 the whole problem of the relation of algae to fish and fish culture is 

 in great need of further detailed investigation. 



SYSTEMATIC ACCOUNT OF THE PHYTOPLANKTON OF PALISADES 



PARK 



In the following list, and in the table of the phytoplankton of the 

 Park (pp. 140-145) the frequency of occurrence in different lakes is 

 designated as follows: (cc) common, (c) fairly common, (s) fairly 

 scarce, (ss) scarce, (sss) very scarce, (r) fairly rare, frr) rare, 

 (rrr) very rare. Since determination of the plankton algae is aided 

 more by figures than by descriptions special attention has been given 

 to the illustration of the plankton algae of the Park (Plates 3-24). 

 New or noteworthy species are as follows : 



Coelosphaerium radiatum sp. nov. PI. 3, Figs. 9-10. 



Colonies containing comparatively few cells, enclosed by a very 

 hyaline, homogeneous, gelatinous envelope. Cells ovoid-pyriform, 

 radially arranged about a common center and with their smaller ends 

 facing outwards. Cells lying some distance from one another. Cell 

 contents homogeneous, pale blue-green in color. 



Cells 5-6 IX long, 1.75-2.0 p. broad: diam. of colonies 16-19 M- 



Popolopen Pond (rr). 



This species is characterized by the peculiar cell shape, the small 

 number of cells in the colony, and by the arrangement of the cells 

 within the colony. 



Synura Adamsii sp. nov. PI. 5. Figs. 4-5. 



Colonies usually spherical, with the cells loosely arranged to form 

 a radiating mass from a common center. Cells elongate club-shaped, 

 with the proximal ends subacute and the anterior portion of the ceil 

 with a few scattered spines. Cells with two elongate, laminate 

 chromatophores and two cilia of equal length. 



Length of cells 42-47 fx, breadth 6.5-10 /x, length of cilia 12-17 jx. 



Little Dam Pond frr), Little Long Pond (r). 



The ratio between breadth and length of the cell in this species is 

 1 :4 to 1 :6 whereas in the common 5^. uvella it is i :2 to i :3.5. The 

 spines on the cell wall do not cover more than the anterior quarter of 

 the cell in this species. 



