THE EUGLENOIDINA OF OHIO 351 



large water weeds. These were in small quantities and were 

 gradually being dredged out after having withstood a considerable 

 amount of a copper sulphate solution. Among the unicellular 

 forms were C entropy xis aculeata, Trachelomonaf< tere^, Entosiphon 

 sulcatum, Cosmarium, Pleurosigma, Spi7illum, etc. In the storage 

 reservoir containing the purified water from immediately above 

 the weir where the water was aerated, were obtained Difflugia 

 const7icta among filaments of Cladopho^^a glomerata, Trachelomo- 

 nas globularis, Amoeba sp., Aspidisca costata, Navicida, Cosma- 

 rium, OsciUatoria, etc. None occurred, however, in quantities 

 which would impart tastes or odors to the water. 



At Hamilton in an uncovered reservoir situated across the 

 river on the hill were found Cladophora crispata submerged on the 

 bottom of the reservoir; Halteria grandinella, Pediastrum tetras, 

 Codonosiga botrytis, Chilomonas Paramecium, species of Plana- 

 rians, etc. 



From the Storage Dam at Columbus numerous species of 

 Paramecium, Amoeba, Euglena, Trachelomonas, Diatoms, etc., as 

 well as Aelosoma, one of the aquatic oligochaetes. 



Other interesting species were found from samples at Lisbon, 

 Cuyahoga Falls, Akron, etc. 



5. Classification. 



(a) HISTORICAL. 



The history of the minute forms of aquatic life is closely con- 

 nected with that of the microscope and may be said to date from 

 Leeuewenhoeck, 1675, who was succeeded by Trembley, 1744; 

 Muller, 1786, and Ehrenberg, 1838. The latter, by aid of im- 

 proved microscopes, worked out details of structure with great 

 care, although erroneously interpreting many of them. For in- 

 stance the red pigment spot — the stigma — so generally found 

 among the Euglenidae was supposed to be actually an eye, while 

 the nerve ganglion which was assumed must accompany it. was 

 described in a species of Astasia. Following Ehrenberg came 

 Duiardin, 1841, who clearly outlined the class Mastigophora 

 (Flagellata) as animals provided with one or more flagella. Later 

 Stein, 1850 ; Kent, 1880, and others who did excellent work taking 



