June, 1919] 



Fauna of Rock Bottom Ponds 



473 



TABLE 24— (Continued). 



Group 



Rotifera 



Protozoa 



Vertebrata 



Algas 



Species 



Distyla ludwigii 



Aneuria cochlearis . . . 

 Aneuria cochlearis 



var. macrocantha. 

 Brachionus bakeri . . . 



Proales decipiens 



Cathy pera luna 



Triartha longiseta 



Rotifera neptunis 



Total Rotifera . 



Ceratium longicorne. 



Dinobyron 



Chilomonas sp 



Euglena viridis 



Pleodorina 



Vorticella sp 



Difflugia corona 



Arcella vulgaris 



Total Protozoa. 



Cyprinus carpio 



Eupoinotis gibbosus. 



Lepomis pallidus 



Lepomis cyanellus. . . 

 Ameiurus natalis. . . . 



Ameiurus sp 



Perca flavescens 



Apomotis cyanellus . , 

 Minnows 



Tadpole (Rana) 



Chrysemis marginata. 

 Sandpiper 



Total Vertebrata . 



Merismopedia . 

 Pediastrum . . . 

 Scenedesmus.. 

 Closterium . . . 



Total Algae . 



Total species . 



Ponds 



Turning now to the plankton, the striking feature shown by 

 the quantitative plankton summary. Table '25, page 474, is a 

 progressive diminution in the total number of individuals per 

 hundred liters, as one passes from the youngest to the oldest 

 member of the series. The figures as given include both the 

 phytoplankton and the zooplankton but even exclusive of the 

 phytoplankton the same relative totals exist. As between the 

 youngest and the oldest pond it will be seen that in the one year 

 pond 99 per cent of the total is composed of protozoa and 

 rotifers, while in the thirty year pond entomostraca comprise 

 85 per cent of the total. In the fifteen year pond entomostraca 

 form a larger percentage of the total although only slightly so. 

 In the ten year pond entomostraca are the most abundant group 

 and are also more numerous than in either of the younger ponds. 



