Lake Maxinkuckee, Physical and Biological Survey 77 



biology, Washington, D. C, high schools, gave the following 



results : 



Species. Per cent. 



Diaptomus oregonensis Lilljeborg' 0.38 



Cyclops leuckarti Claus; {edax Forbes) 4.11 



Diaphanosoma leuchtenbergianum Fischer 0.40 



Daphniii retrocurva Forbes, var 1.06 



DupJinia hyalina Leydig 84 . 02 



99.97 



The Copepods (free-swimming species) frequently bear at- 

 tached Protozoa, sometimes in such numbers as to make them ap- 

 pear bristly. They seem to be more abundant in winter when the 

 lake is covered with ice. Whenever holes are cut through the ice 

 these crustaceans often come crowding to the light and air. 



The Cladocera are, generally speaking, the larger and more 

 showy element of the crustacean plankton. Their stomach con- 

 tents, which at times forms conspicuous masses, was found to be 

 composed largely of phyto-plankton elements, especially Botryo- 

 coccus braunii which, because of its color, was easily recognizable. 

 One of the smaller Cladocera, Chydorus, was found to constitute 

 an important part of the food of the Unionidse or mussels of the 

 lake, as it also does of the small fishes. 



One of the most notable species of the Zoo-plankton was Lepto- 

 dora hyalina. This is usually a deep-water species, but on Sep- 

 tember 2 (1906), it was taken in quantities in a surface tow-net in 

 Outlet Bay. Though one of the largest of the plankton crusta- 

 ceans, this species is so transparent as to be quite invisible except 

 by its movements among the associated individuals of Lyngbya. 



Two other species of Entotomostraca not usually classed as 

 plankton, were noted, namely, the fairy shrimps. One, Branchip- 

 us serratus, was found dead in large numbers floating on the sur- 

 face in deep water July 11 (1899) . Later in the same day, consid- 

 erable numbers were seined in shallow water off Norris Inlet. 

 Again on August 21 and 31, a few were seen floating. 



Another species, Branchipus vernalis, was found abundantly 

 in small temporary ponds west and south of the lake in the spring 

 of 1901. 



A school of these curious crustaceans of delicate structure and 

 pearly appearance, apparently usually swimming on their backs, 

 their numerous gill-feet moving rapidly in the water, makes a 

 very pretty sight. 



The Parasitic Copepods are reported on by Dr. Wilson (pp. 79- 

 82) . It may be here remarked that, as compared with other bodies 



