192 ILLINOIS STATE ACADEMY OF SCIENCE 



GENERAL SURVEY OF THE FAUNA OF LAKE KNOX— Continued. 



Phylum Annelida 



Class Chaetopoda 



Order Oligochaeta 



Family Lumbricidae 



Helodrilus caliginosus 



The common earth worm was found frequent- 

 ly on damp earth on the bank. 

 Family Naididae 

 Chaetogaster 



Several of these were found In the shallow 

 water of Station I. 

 Class Hirudinea 



Order Gnathobdellida 



Family H erpohdellidae 

 Herpohdella punctata 



This leech was found in numbers attached to 

 the under surface of bricks at the mud bot- 

 tomed station in the muskrat region. It 

 was a rather large form characterized by 

 four rows of black spots on the dorsal side. 

 About the middle of May they were found 

 in great numbers at Station I. The little 

 newly hatched ones were very numerous on 

 the under side of bricks in the water, and 

 eggs were plentiful as well. 



Phylum Artliropoda 



Class Crustacea 



Subclass Entomostraca 

 Order Phyllopoda 



Suborder Cladocera 



These water fleas were found in the water of 

 Station V where plant food Is so abundant. 

 Simocephalus 

 Daphnia 



Both of these forms were found in shallow water, some- 

 times on the surface, and sometimes deeper in the 

 water. Daphnia was the more numerous of the two. 

 Order Copepoda 



Cyclops bicuspidatus 



This was found very early in the spring, in "fact as 

 early as March 20th when the water was quite cold. 

 It is a plankton form remaining on the surface. It 

 is found at almost all seasons of the year and often 

 bears great loads of eggs in two little sacs, one on 

 either side near the posterior end of the body. 

 Order Ostracoda 

 Cypris virens 



These small animals, which are enclosed by a shell, 

 belong to the plankton of the pond. The shell is 

 covered with hairs. 

 Subclass Malacostraca 

 Order Amphipoda 



Gammarus faciatus 



This small crustacean was found in March and 

 early April in great numbers in the bottom of 

 Station V and also at Station I. They seem to 

 be unable to survive when taken out of their 

 habitat, for they die very quickly when put In 

 jars of water in the laboratory. 



