Vol. XXI, pp. 91-106 March 21, 1908 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



^•"Ti, | 



* 



THE HOLOPHYTIC PLANKTON OF LAKES ATITLAN 

 AND AMATITLAN, GUATEMALA. 



BY H. WALTON CLARK, 



U. S. Bureau of Fisheries. 



In the present paper is given a list of the chlorophyl-hearing 

 plankton-elements of the lakes Atitlan and Amatitlan, Guate- 

 mala, collected by Dr. Seth E. Meek, of the Field Museum of 

 Natural History, Chicago, during the winter of 1905-1906. 

 Among the material examined were examples of certain plants, 

 Salvinia natans (L.), Oeratophyllum demersum L., Ionardia natans 

 (Ell.) and fragments of Cham, which do not belong to plankton. 



The holophytic animals are included in this report, partly 

 because they are regarded by some authors as plants, but prima- 

 rily because plankton studies are essentially ecological rather 

 than taxonomic, the most important division being that which 

 separates the material according to whether it is self-supporting 

 or whether it depends upon organic matter for subsistence. 



So far as they could be found, references have been given to 

 publications containing figures of each species listed, and in cases 

 where the original description or other important references 

 could be found they have also been cited. 



The attempt has been, not so much to give a complete list of 

 synonyms, as to include, and enable the student to correlate, the 

 names generally known. In looking up the references I have 

 received much assistance from Mr. P. L. Ricker of the U. S. 

 Department of Agriculture, to whom I take this opportunity of 

 expressing my thanks. 



The phytoplankton of lakes Atitlan and Amatitlan, so far as 

 the collections indicate, consists exclusively of algre. None of 

 the minute Lemnacese were found: they are, however, usually 

 14— Proc. Biol. Soc. Wash., Vol. XXI, 1908. (91) 



